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	Author	Muñoz, W.A.; Covaci, L.; Peeters, F.M.
	Title	Tight-binding description of intrinsic superconducting correlations in multilayer graphene			Type	A1 Journal article
	Year	2013	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	87	Issue	13	Pages	134509-7
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Using highly efficient GPU-based simulations of the tight-binding Bogoliubov-de Gennes equations we solve self-consistently for the pair correlation in rhombohedral (ABC) and Bernal (ABA) multilayer graphene by considering a finite intrinsic s-wave pairing potential. We find that the two different stacking configurations have opposite bulk/surface behavior for the order parameter. Surface superconductivity is robust for ABC stacked multilayer graphene even at very low pairing potentials for which the bulk order parameter vanishes, in agreement with a recent analytical approach. In contrast, for Bernal stacked multilayer graphene, we find that the order parameter is always suppressed at the surface and that there exists a critical value for the pairing potential below which no superconducting order is achieved. We considered different doping scenarios and find that homogeneous doping strongly suppresses surface superconductivity while nonhomogeneous field-induced doping has a much weaker effect on the superconducting order parameter. For multilayer structures with hybrid stacking (ABC and ABA) we find that when the thickness of each region is small (few layers), high-temperature surface superconductivity survives throughout the bulk due to the proximity effect between ABC/ABA interfaces where the order parameter is enhanced. DOI: 10.1103/PhysRevB.87.134509
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000317390000006	Publication Date	2013-04-11
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	37	Open Access
	Notes	; This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem funding of the Flemish Government. ;			Approved	Most recent IF: 3.836; 2013 IF: 3.664
	Call Number	UA @ lucian @ c:irua:108469			Serial	3660
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	Author	Muñoz, W.A.; Covaci, L.; Peeters, F.M.
	Title	Tight-binding study of bilayer graphene Josephson junctions			Type	A1 Journal article
	Year	2012	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	86	Issue	18	Pages	184505-184507
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Using highly efficient simulations of the tight-binding Bogoliubov-de-Gennes model, we solved self-consistently for the pair correlation and the Josephson current in a superconducting-bilayer graphene-superconducting Josephson junction. Different doping levels for the non-superconducting link are considered in the short- and long-junction regimes. Self-consistent results for the pair correlation and superconducting current resemble those reported previously for single-layer graphene except at the Dirac point, where remarkable differences in the proximity effect are found, as well as a suppression of the superconducting current in the long-junction regime. Inversion symmetry is broken by considering a potential difference between the layers and we found that the supercurrent can be switched if the junction length is larger than the Fermi length.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000310840400005	Publication Date	2012-11-07
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	13	Open Access
	Notes	; This work was supported by the Flemish Science Foundation (FWO-VI). ;			Approved	Most recent IF: 3.836; 2012 IF: 3.767
	Call Number	UA @ lucian @ c:irua:105149			Serial	3661
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	Author	de Sousa, J.S.; Covaci, L.; Peeters, F.M.; Farias, G.A.
	Title	Time-dependent investigation of charge injection in a quantum dot containing one electron			Type	A1 Journal article
	Year	2012	Publication	Journal of applied physics	Abbreviated Journal	J Appl Phys
	Volume	112	Issue	9	Pages	093705-93709
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The interaction of an injected electron towards a quantum dot (QD) containing a single confined electron is investigated using a flexible time-dependent quantum mechanics formalism, which allows both electrons to move and undergo quantum transitions. Different scenarios combining quantum dot dimensions, dielectric constant, injected wave packet energy, and width were explored, and our main results are: (i) due to the large characteristic transitions times between the confined state in the quantum dot and the delocalized state in the continuum, it is relatively difficult to ionize the occupied QD by Coulomb interaction solely and (ii) the charging state of the quantum dot can be sensed by direct injection of charges. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4759292]
	Address
	Corporate Author				Thesis
	Publisher	American Institute of Physics	Place of Publication	New York, N.Y.	Editor
	Language		Wos	000311968400052	Publication Date	2012-11-06
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-8979;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.068	Times cited	1	Open Access
	Notes	; This work was financially supported by the Brazilian National Research Council (CNPq), under Contract No. NanoBioEstruturas 555183/2005-0, Fundao Cearense de Apoio ao Desenvolvimento Cientfico e Tecnolgico (Funcap), CAPES, Pronex/CNPq/ Funcap, the Bilateral program between Flanders and Brazil, and the Flemish Science Foundation (FWO). ;			Approved	Most recent IF: 2.068; 2012 IF: 2.210
	Call Number	UA @ lucian @ c:irua:106014			Serial	3664
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	Author	Zhang, L.-F.; Covaci, L.; Peeters, F.M.
	Title	Tomasch effect in nanoscale superconductors			Type	A1 Journal article
	Year	2015	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	91	Issue	91	Pages	024508
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The Tomasch effect (TE) is due to quasiparticle interference (QPI) as induced by a nonuniform superconducting order parameter, which results in oscillations in the density of states (DOS) at energies above the superconducting gap. Quantum confinement in nanoscale superconductors leads to an inhomogenerous distribution of the Cooperpair condensate, which, as we found, triggers the manifestation of a new TE. We investigate the electronic structure of nanoscale superconductors by solving the Bogoliubov-de Gennes (BdG) equations self-consistently and describe the TE determined by two types of processes, involving two-or three-subband QPIs. Both types of QPIs result in additional BCS-like Bogoliubov-quasiparticles and BCS-like energy gaps leading to oscillations in the DOS and modulated wave patterns in the local density of states. These effects are strongly related to the symmetries of the system. A reduced 4 x 4 inter-subband BdG Hamiltonian is established in order to describe analytically the TE of two-subband QPIs. Our study is relevant to nanoscale superconductors, either nanowires or thin films, Bose-Einsten condensates, and confined systems such as two-dimensional electron gas interface superconductivity.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Lancaster, Pa	Editor
	Language		Wos	000348473700003	Publication Date	2015-01-16
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	6	Open Access
	Notes	; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Methusalem funding of the Flemish Government. ;			Approved	Most recent IF: 3.836; 2015 IF: 3.736
	Call Number	c:irua:123864			Serial	3670
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	Author	Zhang, L.-F.; Covaci, L.; Milošević, M.V.; Berdiyorov, G.R.; Peeters, F.M.
	Title	Unconventional vortex states in nanoscale superconductors due to shape-induced resonances in the inhomogeneous Cooper-pair condensate			Type	A1 Journal article
	Year	2012	Publication	Physical review letters	Abbreviated Journal	Phys Rev Lett
	Volume	109	Issue	10	Pages	107001
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Vortex matter in mesoscopic superconductors is known to be strongly affected by the geometry of the sample. Here we show that in nanoscale superconductors with coherence length comparable to the Fermi wavelength the shape resonances of the order parameter results in an additional contribution to the quantum topological confinement-leading to unconventional vortex configurations. Our Bogoliubov-de Gennes calculations in a square geometry reveal a plethora of asymmetric, giant multivortex, and vortex-antivortex structures, stable over a wide range of parameters and which are very different from those predicted by the Ginzburg-Landau theory. These unconventional states are relevant for high-T-c nanograins, confined Bose-Einstein condensates, and graphene flakes with proximity-induced superconductivity.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	New York, N.Y.	Editor
	Language		Wos	000308295700014	Publication Date	2012-09-05
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0031-9007;1079-7114;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	8.462	Times cited	31	Open Access
	Notes	; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen). ;			Approved	Most recent IF: 8.462; 2012 IF: 7.943
	Call Number	UA @ lucian @ c:irua:101850			Serial	3801
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	Author	Richardson, C.L.; Edkins, S.D.; Berdiyorov, G.R.; Chua, C.J.; Griffiths, J.P.; Jones, G.A.C.; Buitelaar, M.R.; Narayan, V.; Sfigakis, F.; Smith, C.G.; Covaci, L.; Connolly, M.R.;
	Title	Vortex detection and quantum transport in mesoscopic graphene Josephson-junction arrays			Type	A1 Journal article
	Year	2015	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	91	Issue	91	Pages	245418
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	We investigate mesoscopic Josephson-junction arrays created by patterning superconducting disks on monolayer graphene, concentrating on the high-T/T-c regime of these devices and the phenomena which contribute to the superconducting glass state in diffusive arrays. We observe features in the magnetoconductance at rational fractions of flux quanta per array unit cell, which we attribute to the formation of flux-quantized vortices. The applied fields at which the features occur are well described by Ginzburg-Landau simulations that take into account the number of unit cells in the array. We find that the mean conductance and universal conductance fluctuations are both enhanced below the critical temperature and field of the superconductor, with greater enhancement away from the graphene Dirac point.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000356129800012	Publication Date	2015-06-15
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	2	Open Access
	Notes	; This work was financially supported by the Engineering and Physical Sciences Research Council, and an NPL/EPSRC Joint Postdoctoral Partnership. Supporting data for this paper is available at the DSpace@Cambridge data repository (https://www.repository.cam.ac.uk/handle/1810/248242). ;			Approved	Most recent IF: 3.836; 2015 IF: 3.736
	Call Number	c:irua:126982			Serial	3865
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	Author	Zhang, L.-F.; Covaci, L.; Milošević, M.V.; Berdiyorov, G.R.; Peeters, F.M.
	Title	Vortex states in nanoscale superconducting squares : the influence of quantum confinement			Type	A1 Journal article
	Year	2013	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	88	Issue	14	Pages	144501
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Bogoliubov-de Gennes theory is used to investigate the effect of the size of a superconducting square on the vortex states in the quantum confinement regime. When the superconducting coherence length is comparable to the Fermi wavelength, the shape resonances of the superconducting order parameter have strong influence on the vortex configuration. Several unconventional vortex states, including asymmetric ones, giant-multivortex combinations, and states comprising giant antivortices, were found as ground states and their stability was found to be very sensitive on the value of k(F)xi(0), the size of the sample W, and the magnetic flux Phi. By increasing the temperature and/or enlarging the size of the sample, quantum confinement is suppressed and the conventional mesoscopic vortex states as predicted by the Ginzburg-Laudau (GL) theory are recovered. However, contrary to the GL results we found that the states containing symmetry-induced vortex-antivortex pairs are stable over the whole temperature range. It turns out that the inhomogeneous order parameter induced by quantum confinement favors vortex-antivortex molecules, as well as giant vortices with a rich structure in the vortex core-unattainable in the GL domain.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000325498300004	Publication Date	2013-10-09
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	19	Open Access
	Notes	; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and Methusalem Funding of the Flemish government. ;			Approved	Most recent IF: 3.836; 2013 IF: 3.664
	Call Number	UA @ lucian @ c:irua:111145			Serial	3891
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	Author	Chaves, A.; Covaci, L.; Rakhimov, K.Y.; Farias, G.A.; Peeters, F.M.
	Title	Wave-packet dynamics and valley filter in strained graphene			Type	A1 Journal article
	Year	2010	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	82	Issue	20	Pages	205430
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The time evolution of a wave packet in strained graphene is studied within the tight-binding model and continuum model. The effect of an external magnetic field, as well as a strain-induced pseudomagnetic field, on the wave-packet trajectories and zitterbewegung are analyzed. Combining the effects of strain with those of an external magnetic field produces an effective magnetic field which is large in one of the Dirac cones, but can be practically zero in the other. We construct an efficient valley filter, where for a propagating incoming wave packet consisting of momenta around the K and K' Dirac points, the outgoing wave packet exhibits momenta in only one of these Dirac points while the components of the packet that belong to the other Dirac point are reflected due to the Lorentz force. We also found that the zitterbewegung is permanent in time in the presence of either external or strain-induced magnetic fields, but when both the external and strain-induced magnetic fields are present, the zitterbewegung is transient in one of the Dirac cones, whereas in the other cone the wave packet exhibits permanent spatial oscillations.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000284401600007	Publication Date	2010-11-19
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	95	Open Access
	Notes	; This work was financially supported by CNPq under NanoBioEstruturas Contract No. 555183/2005-0, PRONEX/CNPq/FUNCAP, CAPES, the Bilateral program between Flanders and Brazil, the Belgian Science Policy (IAP), and the Flemish Science Foundation (FWO-V1) ;			Approved	Most recent IF: 3.836; 2010 IF: 3.774
	Call Number	UA @ lucian @ c:irua:95542			Serial	3905
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	Author	da Costa, D.R.; Chaves, A.; Farias, G.A.; Covaci, L.; Peeters, F.M.
	Title	Wave-packet scattering on graphene edges in the presence of a pseudomagnetic field			Type	A1 Journal article
	Year	2012	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	86	Issue	11	Pages	115434
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The scattering of a Gaussian wave packet in armchair and zigzag graphene edges is theoretically investigated by numerically solving the time-dependent Schrodinger equation for the tight-binding model Hamiltonian. Our theory allows us to investigate scattering in reciprocal space, and depending on the type of graphene edge we observe scattering within the same valley, or between different valleys. In the presence of an external magnetic field, the well-known skipping orbits are observed. However, our results demonstrate that in the case of a pseudomagnetic field, induced by nonuniform strain, the scattering by an armchair edge results in a nonpropagating edge state.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000309174100005	Publication Date	2012-09-21
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121;1550-235X;	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	28	Open Access
	Notes	; Discussions with E. B. Barros are gratefully acknowledged. This work was supported by the Brazilian Council for Research (CNPq), the Flemish Science Foundation (FWO-Vl), the ESF-EuroGRAPHENE (project CONGRAN), and the bilateral program between Flanders and Brazil. ;			Approved	Most recent IF: 3.836; 2012 IF: 3.767
	Call Number	UA @ lucian @ c:irua:101833			Serial	3907
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	Author	Dell'Anna, L.; Perali, A.; Covaci, L.; Neilson, D.
	Title	Using magnetic stripes to stabilize superfluidity in electron-hole double monolayer graphene			Type	A1 Journal article
	Year	2015	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	92	Issue	92	Pages	220502
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Experiments have confirmed that double monolayer graphene does not generate finite-temperature electron-hole superfluidity, because of very strong screening of the pairing attraction. The linear dispersing energy bands in monolayer graphene block any attempt to reduce the strength of the screening. We propose a hybrid device with two sheets of monolayer graphene in a modulated periodic perpendicular magnetic field. The field preserves the isotropic Dirac cones of the original monolayers but reduces the slope of the cones, making the monolayer Fermi velocity v(F) smaller. We demonstrate that with current experimental techniques, the reduction in vF can weaken the screening sufficiently to allow electron-hole superfluidity at measurable temperatures.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000366500100004	Publication Date	2015-12-14
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	7	Open Access
	Notes	; We thank M. Zarenia for useful discussions. L.D. acknowledges financial support from MIUR: FIRB 2012, Grant No. RBFR12NLNA_002, and PRIN, Grant No. 2010LLKJBX. A.P. and D.N. acknowledge financial support from University of Camerino FAR project CESEMN. L.C. acknowledges financial support from Flemish Science Foundation (FWO). ;			Approved	Most recent IF: 3.836; 2015 IF: 3.736
	Call Number	c:irua:130211			Serial	4069
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	Author	Homm, P.; Dillemans, L.; Menghini, M.; Van Bilzen, B.; Bakalov, P.; Su, C.Y.; Lieten, R.; Houssa, M.; Nasr Esfahani, D.; Covaci, L.; Peeters, F.M.; Seo, J.W.; Locquet, J.P.;
	Title	Collapse of the low temperature insulating state in Cr-doped V₂O₃ thin films			Type	A1 Journal article
	Year	2015	Publication	Applied physics letters	Abbreviated Journal	Appl Phys Lett
	Volume	107	Issue	107	Pages	111904
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	We have grown epitaxial Cr-doped V2O3 thin films with Cr concentrations between 0% and 20% on (0001)-Al2O3 by oxygen-assisted molecular beam epitaxy. For the highly doped samples (>3%), a regular and monotonous increase of the resistance with decreasing temperature is measured. Strikingly, in the low doping samples (between 1% and 3%), a collapse of the insulating state is observed with a reduction of the low temperature resistivity by up to 5 orders of magnitude. A vacuum annealing at high temperature of the films recovers the low temperature insulating state for doping levels below 3% and increases the room temperature resistivity towards the values of Cr-doped V2O3 single crystals. It is well-know that oxygen excess stabilizes a metallic state in V2O3 single crystals. Hence, we propose that Cr doping promotes oxygen excess in our films during deposition, leading to the collapse of the low temperature insulating state at low Cr concentrations. These results suggest that slightly Cr-doped V2O3 films can be interesting candidates for field effect devices. (C) 2015 AIP Publishing LLC.
	Address
	Corporate Author				Thesis
	Publisher	American Institute of Physics	Place of Publication	New York, N.Y.	Editor
	Language		Wos	000361639200020	Publication Date	2015-09-19
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0003-6951; 1077-3118	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.411	Times cited	14	Open Access
	Notes	; The authors acknowledge financial support from the FWO Project No. G052010N10 as well as the EU-FP7 SITOGA Project. P.H. acknowledges support from Becas Chile-CONICYT. ;			Approved	Most recent IF: 3.411; 2015 IF: 3.302
	Call Number	UA @ lucian @ c:irua:128728			Serial	4149
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	Author	Zha, G.-Q.; Covaci, L.; Peeters, F.M.; Zhou, S.-P.
	Title	Majorana zero-energy modes and spin current evolution in mesoscopic superconducting loop systems with spin-orbit interaction			Type	A1 Journal article
	Year	2015	Publication	Physical review : B : condensed matter and materials physics	Abbreviated Journal	Phys Rev B
	Volume	92	Issue	92	Pages	094516
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The Majorana zero modes and persistent spin current in mesoscopic d-wave-superconducting loops with spin-orbit (SO) interaction are investigated by numerically solving the spin-generalized Bogoliubov-de Gennes equations self-consistently. For some appropriate strength of the SO coupling, Majorana zero-energy states and sharp jumps of the spin-polarized currents can be observed when the highest energy levels cross the Fermi energy in the spectrum, leading to spin currents with opposite chirality flowing near the inner and outer edges of the sample. When the threaded magnetic flux turns on, four flux-dependent patterns of the persistent spin current with step-like features show up, accompanied by Majorana edge modes at flux values where the energy gap closes. Moreover, the Majorana zero mode is highly influenced by the direction of the Zeeman field. A finite in-plane field can lead to the gap opening since the inversion symmetry is broken. Remarkably, multiple Majorana zero-energy states occur in the presence of an out-of-plane field h(z), and the number of steps in the spin current evolution can be effectively tuned by the field strength due to the shift of Majorana zero modes. Finally, when the loop sample contains surface indentation defects, zero-energy modes can always show up in the presence of an appropriate h(z). Interestingly, multiple Majorana states may be present in the system with a corner defect even if h(z) = 0.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Lancaster, Pa	Editor
	Language		Wos	000362081000002	Publication Date	2015-09-30
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1098-0121; 1550-235x	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	11	Open Access
	Notes	; This work was supported by National Natural Science Foundation of China under Grants No. 61371020, No. 61271163, and No. 61571277, by the Visiting Scholar Program of Shanghai Municipal Education Commission, and by the Flemish Science Foundation (FWO-Vl). ;			Approved	Most recent IF: 3.836; 2015 IF: 3.736
	Call Number	UA @ lucian @ c:irua:132467			Serial	4203
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	Author	Zhang, L.-F.; Covaci, L.; Peeters, F.M.
	Title	Position-dependent effect of non-magnetic impurities on superconducting properties of nanowires			Type	A1 Journal article
	Year	2015	Publication	Europhysics letters	Abbreviated Journal	Epl-Europhys Lett
	Volume	109	Issue	109	Pages	17010
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Anderson's theorem states that non-magnetic impurities do not change the bulk properties of conventional superconductors. However, as the dimensionality is reduced, the effect of impurities becomes more significant. Here we investigate superconducting nanowires with diameter comparable to the Fermi wavelength $\lambda_F$ (which is less than the superconducting coherence length) by using a microscopic description based on the Bogoliubov-de Gennes method. We find that: 1) impurities strongly affect the superconducting properties, 2) the effect is impurity position dependent, and 3) it exhibits opposite behavior for resonant and off-resonant wire widths. We show that this is due to the interplay between the shape resonances of the order parameter and the subband energy spectrum induced by the lateral quantum confinement. These effects can be used to manipulate the Josephson current, filter electrons by subband and investigate the symmetries of the superconducting subband gaps.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication	Paris	Editor
	Language		Wos	000348592100029	Publication Date	2015-01-21
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0295-5075	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	1.957	Times cited	7	Open Access
	Notes	; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Methusalem funding of the Flemish Government. ;			Approved	Most recent IF: 1.957; 2015 IF: 2.095
	Call Number	UA @ lucian @ c:irua:128424			Serial	4227
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	Author	Zhang, L.; Fernández Becerra, V.; Covaci, L.; Milošević, M.V.
	Title	Electronic properties of emergent topological defects in chiral p-wave superconductivity			Type	A1 Journal article
	Year	2016	Publication	Physical review B	Abbreviated Journal	Phys Rev B
	Volume	94	Issue	94	Pages	024520
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Chiral p-wave superconductors in applied magnetic field can exhibit more complex topological defects than just conventional superconducting vortices, due to the two-component order parameter (OP) and the broken time-reversal symmetry. We investigate the electronic properties of those exotic states, some of which contain clusters of one-component vortices in chiral components of the OP and/or exhibit skyrmionic character in the relative OP space, all obtained as a self-consistent solution of the microscopic Bogoliubov-de Gennes equations. We reveal the link between the local density of states (LDOS) of the novel topological states and the behavior of the chiral domain wall between the OP components, enabling direct identification of those states in scanning tunneling microscopy. For example, a skyrmion always contains a closed chiral domain wall, which is found to be mapped exactly by zero-bias peaks in LDOS. Moreover, the LDOS exhibits electron-hole asymmetry, which is different from the LDOS of conventional vortex states with same vorticity. Finally, we present the magnetic field and temperature dependence of the properties of a skyrmion, indicating that this topological defect can be surprisingly large in size, and can be pinned by an artificially indented nonsuperconducting closed path in the sample. These features are expected to facilitate the experimental observation of skyrmionic states, thereby enabling experimental verification of chirality in emerging superconducting materials.
	Address
	Corporate Author				Thesis
	Publisher	American Physical Society	Place of Publication	New York, N.Y	Editor
	Language		Wos	000381479500002	Publication Date	2016-07-26
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9969	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	27	Open Access
	Notes	; This work was supported by the Fonds Wetenschappelijk Onderzoek (FWO). ;			Approved	Most recent IF: 3.836
	Call Number	UA @ lucian @ c:irua:135742			Serial	4303
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	Author	Zhang, L.-F.; Flammia, L.; Covaci, L.; Perali, A.; Milošević, M.V.
	Title	Multifaceted impact of a surface step on superconductivity in atomically thin films			Type	A1 Journal article
	Year	2017	Publication	Physical review B	Abbreviated Journal	Phys Rev B
	Volume	96	Issue	10	Pages	104509
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Recent experiments show that an atomic step on the surface of atomically thin metallic films can strongly affect electronic transport. Here we reveal multiple and versatile effects that such a surface step can have on superconductivity in ultrathin films. By solving the Bogoliubov-de Gennes equations self-consistently in this regime, where quantum confinement dominates the emergent physics, we show that the electronic structure is profoundly modified on the two sides of the step, as is the spatial distribution of the superconducting order parameter and its dependence on temperature and electronic gating. Furthermore, the surface step changes nontrivially the transport properties both in the proximity-induced superconducting pair correlations and the Josephson effect, depending on the step height. These results offer a new route to tailor superconducting circuits and design atomically thin heterojunctions made of one same material.
	Address
	Corporate Author				Thesis
	Publisher	American Physical Society	Place of Publication	New York, N.Y	Editor
	Language		Wos	000411076000012	Publication Date	2017-09-18
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	7	Open Access
	Notes	; This work was supported by the Research Foundation Flanders (FWO-Vlaanderen), the Special Research Funds of the University of Antwerp (TOPBOF project) and the Italian MIUR through the PRIN 2015 program (Contract No. 2015C5SEJJ001). ;			Approved	Most recent IF: 3.836
	Call Number	UA @ lucian @ c:irua:146750			Serial	4790
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	Author	Lane, T.L.M.; Andelkovic, M.; Wallbank, J.R.; Covaci, L.; Peeters, F.M.; Fal'ko, V.I.
	Title	Ballistic electron channels including weakly protected topological states in delaminated bilayer graphene			Type	A1 Journal article
	Year	2018	Publication	Physical review B	Abbreviated Journal	Phys Rev B
	Volume	97	Issue	4	Pages	045301
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	<script type='text/javascript'>document.write(unpmarked('We show that delaminations in bilayer graphene (BLG) with electrostatically induced interlayer symmetry can provide one with ballistic channels for electrons with energies inside the electrostatically induced BLG gap. These channels are formed by a combination of valley-polarized evanescent states propagating along the delamination edges (which persist in the presence of a strong magnetic field) and standing waves bouncing between them inside the delaminated region (in a strong magnetic field, these transform into Landau levels in the monolayers). For inverted stackings in BLGs on the left and right of the delamination (AB-2ML-BA or BA-2ML-AB, where 2ML indicates two decoupled monolayers of graphene), the lowest-energy ballistic channels are gapless, have linear dispersion, and appear to be weakly topologically protected. When BLG stackings on both sides of the delamination are the same (AB-2ML-AB or BA-2ML-BA), the lowest-energy ballistic channels are gapped, with a gap epsilon(g) scaling as epsilon(g) alpha W-1 with delamination width and epsilon(g) alpha delta(-1) with the on-layer energy difference in the delaminated part of the structure. Depending on the width, delaminations may also support several \u0022higher-energy\u0022 waveguide modes. Our results are based on both the analytical study of the wave matching of Dirac states and tight-binding model calculations, and we analyze in detail the dependence of the delamination spectrum on the electrostatic conditions in the structure, such as the vertical displacement field.'));
	Address
	Corporate Author				Thesis
	Publisher	American Physical Society	Place of Publication	New York, N.Y	Editor
	Language		Wos	000419772200005	Publication Date	2018-01-11
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	11	Open Access
	Notes	; This work was funded by EPSRC via EPSRC Grand Engineering Chellenges Grant No. EP/N010345, the Manchester NOWNANO CDT EP/L-1548X, the Flemish Science Foundation (FWO-VI), the European Graphene Flagship project, ERC Synergy grant Hetero2D, and FLAG-ERA project TRANS2DTMD. The authors would like to acknowledge useful discussions with M. Zarenia, S. Slizovskiy, E. McCann, and K. Novesolov. ;			Approved	Most recent IF: 3.836
	Call Number	UA @ lucian @ c:irua:148441UA @ admin @ c:irua:148441			Serial	4868
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	Author	Zhang, L.-F.; Covaci, L.; Milošević, M.V.
	Title	Topological phase transitions in small mesoscopic chiral p-wave superconductors			Type	A1 Journal article
	Year	2017	Publication	Physical review B	Abbreviated Journal	Phys Rev B
	Volume	96	Issue	22	Pages	224512
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	<script type='text/javascript'>document.write(unpmarked('Spin-triplet chiral p-wave superconductivity is typically described by a two-component order parameter, and as such is prone to unique emergent effects when compared to the standard single-component superconductors. Here we present the equilibrium phase diagram for small mesoscopic chiral p-wave superconducting disks in the presence of magnetic field, obtained by solving the microscopic Bogoliubov-de Gennes equations self-consistently. In the ultrasmall limit, the cylindrically symmetric giant-vortex states form the ground state of the system. However, with increasing sample size, the cylindrical symmetry is broken as the two components of the order parameter segregate into domains, and the number of fragmented domain walls between them characterizes the resulting states. Such domain walls are topological defects unique for the p-wave order, and constitute a dominant phase in the mesoscopic regime. Moreover, we find two possible types of domain walls, identified by their chirality-dependent interaction with the edge states.'));
	Address
	Corporate Author				Thesis
	Publisher	American Physical Society	Place of Publication	New York, N.Y	Editor
	Language		Wos	000418653500012	Publication Date	2017-12-26
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	18	Open Access
	Notes	; This work was supported by the Research Foundation Flanders (FWO-Vlaanderen) and the Special Research Funds of the University of Antwerp. ;			Approved	Most recent IF: 3.836
	Call Number	UA @ lucian @ c:irua:148504			Serial	4901
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	Author	Andelkovic, M.; Covaci, L.; Peeters, F.M.
	Title	DC conductivity of twisted bilayer graphene: Angle-dependent transport properties and effects of disorder			Type	A1 Journal article
	Year	2018	Publication	Physical review materials	Abbreviated Journal
	Volume	2	Issue	3	Pages	034004
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The in-plane dc conductivity of twisted bilayer graphene is calculated using an expansion of the real-space Kubo-Bastin conductivity in terms of Chebyshev polynomials. We investigate within a tight-binding approach the transport properties as a function of rotation angle, applied perpendicular electric field, and vacancy disorder. We find that for high-angle twists, the two layers are effectively decoupled, and the minimum conductivity at the Dirac point corresponds to double the value observed in monolayer graphene. This remains valid even in the presence of vacancies, hinting that chiral symmetry is still preserved. On the contrary, for low twist angles, the conductivity at the Dirac point depends on the twist angle and is not protected in the presence of disorder. Furthermore, for low angles and in the presence of an applied electric field, we find that the chiral boundary states emerging between AB and BA regions contribute to the dc conductivity, despite the appearance of localized states in the AA regions. The results agree qualitatively with recent transport experiments in low-angle twisted bilayer graphene.
	Address
	Corporate Author				Thesis
	Publisher	American Physical Society	Place of Publication	College Park, Md	Editor
	Language		Wos	000427822700002	Publication Date	2018-03-20
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2475-9953	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor		Times cited	27	Open Access
	Notes	; We acknowledge financial support from the graphene FLAG-ERA project TRANS2DTMD. ;			Approved	Most recent IF: NA
	Call Number	UA @ lucian @ c:irua:150838UA @ admin @ c:irua:150838			Serial	4964
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	Author	Flammia, L.; Zhang, L.-F.; Covaci, L.; Perali, A.; Milošević, M.V.
	Title	Superconducting nanoribbon with a constriction : a quantum-confined Josephson junction			Type	A1 Journal article
	Year	2018	Publication	Physical review B	Abbreviated Journal	Phys Rev B
	Volume	97	Issue	13	Pages	134514
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	Extended defects are known to strongly affect nanoscale superconductors. Here, we report the properties of superconducting nanoribbons with a constriction formed between two adjacent step edges by solving the Bogoliubov-de Gennes equations self-consistently in the regime where quantum confinement is important. Since the quantum resonances of the superconducting gap in the constricted area are different from the rest of the nanoribbon, such constriction forms a quantum-confined S-S'-S Josephson junction, with a broadly tunable performance depending on the length and width of the constriction with respect to the nanoribbon, and possible gating. These findings provide an intriguing approach to further tailor superconducting quantum devices where Josephson effect is of use.
	Address
	Corporate Author				Thesis
	Publisher	American Physical Society	Place of Publication	New York, N.Y	Editor
	Language		Wos	000430161500004	Publication Date	2018-04-17
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	7	Open Access
	Notes	; This work was supported by the Research Foundation Flanders (FWO-Vlaanderen), the Special Research Funds of the University of Antwerp (TOPBOF), the Italian MIUR through the PRIN 2015 program (Contract No. 2015C5SEJJ001), the MultiSuper network, and the EU-COST NANOCOHYBRI action CA16218. ;			Approved	Most recent IF: 3.836
	Call Number	UA @ lucian @ c:irua:150754UA @ admin @ c:irua:150754			Serial	4980
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	Author	Milovanović, S.P.; Covaci, L.; Peeters, F.M.
	Title	Strain fields in graphene induced by nanopillar mesh			Type	A1 Journal article
	Year	2019	Publication	Journal of applied physics	Abbreviated Journal	J Appl Phys
	Volume	125	Issue	8	Pages	082534
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	The mechanical and electronic properties of a graphene membrane placed on top of a triangular superlattice of nanopillars are investigated. We use molecular dynamics simulations to access the deformation fields and the tight-binding approaches to calculate the electronic properties. Ripples form in the graphene layer that span across the unit cell, connecting neighboring pillars, in agreement with recent experiments. We find that the resulting pseudo-magnetic field (PMF) varies strongly across the unit cell. We investigate the dependence of PMF on unit cell boundary conditions, height of the pillars, and the strength of the van der Waals interaction between graphene and the substrate. We find direct correspondence with typical experiments on pillars, showing intrinsic “slack” in the graphene membrane. PMF values are confirmed by the local density of states calculations performed at different positions of the unit cell showing pseudo-Landau levels with varying spacings. Our findings regarding the relaxed membrane configuration and the induced strains are transferable to other flexible 2D membranes.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000460033800038	Publication Date	2019-01-16
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-8979; 1089-7550	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	2.068	Times cited	5	Open Access
	Notes	; S.P.M. is supported by the Flemish Science Foundation (FWO). ;			Approved	Most recent IF: 2.068
	Call Number	UA @ admin @ c:irua:158605			Serial	5231
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	Author	Pandey, T.; Covaci, L.; Milošević, M.V.; Peeters, F.M.
	Title	Flexoelectricity and transport properties of phosphorene nanoribbons under mechanical bending			Type	A1 Journal article
	Year	2021	Publication	Physical Review B	Abbreviated Journal	Phys Rev B
	Volume	103	Issue	23	Pages	235406
	Keywords	A1 Journal article; Condensed Matter Theory (CMT)
	Abstract	We examine from first principles the flexoelectric properties of phosphorene nanoribbons under mechanical bending along armchair and zigzag directions. In both cases we find that the radial polarization depends linearly on the strain gradient. The flexoelectricity along the armchair direction is over 40% larger than along the zigzag direction. The obtained flexoelectric coefficients of phosphorene are four orders of magnitude larger than those of graphene and comparable to transition metal dichalcogenides. Analysis of charge density shows that the flexoelectricity mainly arises from the pz orbitals of phosphorus atoms. The electron mobilities in bent phosphorene can be enhanced by over 60% along the armchair direction, which is significantly higher than previous reports of mobility tuned by uniaxial strain. Our results indicate phosphorene is a candidate for a two-dimensional material applicable in flexible-electronic devices.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000657129800006	Publication Date	2021-06-02
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.836	Times cited	8	Open Access	Not_Open_Access
	Notes				Approved	Most recent IF: 3.836
	Call Number	UA @ admin @ c:irua:179109			Serial	6996
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	Author	Kourmoulakis, G.; Michail, A.; Paradisanos, I.; Marie, X.; Glazov, M.M.; Jorissen, B.; Covaci, L.; Stratakis, E.; Papagelis, K.; Parthenios, J.; Kioseoglou, G.
	Title	Biaxial strain tuning of exciton energy and polarization in monolayer WS2			Type	A1 Journal Article
	Year	2023	Publication	Applied Physics Letters	Abbreviated Journal
	Volume	123	Issue	22	Pages
	Keywords	A1 Journal Article; Condensed Matter Theory (CMT) ;
	Abstract	We perform micro-photoluminescence and Raman experiments to examine the impact of biaxial tensile strain on the optical properties of WS2 monolayers. A strong shift on the order of −130 meV per % of strain is observed in the neutral exciton emission at room temperature. Under near-resonant excitation, we measure a monotonic decrease in the circular polarization degree under the applied strain. We experimentally separate the effect of the strain-induced energy detuning and evaluate the pure effect coming from the biaxial strain. The analysis shows that the suppression of the circular polarization degree under the biaxial strain is related to an interplay of energy and polarization relaxation channels as well as to variations in the exciton oscillator strength affecting the long-range exchange interaction.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	001124156400003	Publication Date	2023-11-27
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0003-6951	ISBN		Additional Links	UA library record; WoS full record
	Impact Factor	4	Times cited		Open Access
	Notes	Hellenic Foundation for Research and Innovation, HFRI-FM17-3034 ;			Approved	Most recent IF: 4; 2023 IF: 3.411
	Call Number	CMT @ cmt @c:irua:202178			Serial	8991
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	Author	Chaves, A.; Moura, V.N.; Linard, F.J.A.; Covaci, L.; Milošević, M.V.
	Title	Tunable magnetic focusing using Andreev scattering in superconductor-graphene hybrid devices			Type	A1 Journal article
	Year	2020	Publication	Journal Of Applied Physics	Abbreviated Journal	J Appl Phys
	Volume	128	Issue	12	Pages	124303
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We perform the wavepacket dynamics simulation of a graphene-based device where propagating electron trajectories are tamed by an applied magnetic field toward a normal/superconductor interface. The magnetic field controls the incidence angle of the incoming electronic wavepacket at the interface, which results in the tunable electron-hole ratio in the reflected wave function due to the angular dependence of the Andreev reflection. Here, mapped control of the quasiparticle trajectories by the external magnetic field not only defines an experimental probe for fundamental studies of the Andreev reflection in graphene but also lays the foundation for further development of magnetic focusing devices based on nanoengineered superconducting two-dimensional materials.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000576393200002	Publication Date	2020-09-28
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0021-8979; 1089-7550	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.2	Times cited	1	Open Access	Not_Open_Access
	Notes	; This work was supported by the Brazilian Council for Research (CNPq) through the PRONEX/FUNCAP and PQ programs and by the Research Foundation-Flanders (FWO). ;			Approved	Most recent IF: 3.2; 2020 IF: 2.068
	Call Number	UA @ admin @ c:irua:172730			Serial	6639
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	Author	Milovanović, S.P.; Andelkovic, M.; Covaci, L.; Peeters, F.M.
	Title	Band flattening in buckled monolayer graphene			Type	A1 Journal article
	Year	2020	Publication	Physical Review B	Abbreviated Journal	Phys Rev B
	Volume	102	Issue	24	Pages	245427
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	The strain fields of periodically buckled graphene induce a periodic pseudomagnetic field (PMF) that modifies the electronic band structure. From the geometry, amplitude, and period of the periodic pseudomagnetic field, we determine the necessary conditions to access the regime of correlated phases by examining the band flattening. As compared to twisted bilayer graphene the proposed system has the advantages that (1) only a single layer of graphene is needed, (2) one is not limited to hexagonal superlattices, and (3) narrower flat bandwidth and larger separation between flat bands can be induced. We, therefore, propose that periodically strained graphene single layers can become a platform for the exploration of exotic many-body phases.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000602844600007	Publication Date	2020-12-28
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.7	Times cited	11	Open Access	OpenAccess
	Notes	; S.P.M. is supported by the Flemish Science Foundation (FWO). We thank E. Y. Andrei, Y. Jiang, and J. Mao for fruitful discussions. ;			Approved	Most recent IF: 3.7; 2020 IF: 3.836
	Call Number	UA @ admin @ c:irua:175021			Serial	6684
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	Author	Pandey, T.; Covaci, L.; Peeters, F.M.
	Title	Tuning flexoelectricty and electronic properties of zig-zag graphene nanoribbons by functionalization			Type	A1 Journal article
	Year	2021	Publication	Carbon	Abbreviated Journal	Carbon
	Volume	171	Issue		Pages	551-559
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	The flexoelectric and electronic properties of zig-zag graphene nanoribbons are explored under mechanical bending using state of the art first principles calculations. A linear dependence of the bending induced out of plane polarization on the applied strain gradient is found. The inferior flexoelectric properties of graphene nanoribbons can be improved by more than two orders of magnitude by hydrogen and fluorine functionalization (CH and CF nanoribbons). A large out of plane flexoelectric effect is predicted for CF nanoribbons. The origin of this enhancement lies in the electro-negativity difference between carbon and fluorine atoms, which breaks the out of plane charge symmetry even for a small strain gradient. The flexoelectric effect can be further improved by co-functionalization with hydrogen and fluorine (CHF Janus-type nanoribbon), where a spontaneous out of plane dipole moment is formed even for flat nanoribbons. We also find that bending can control the charge localization of valence band maxima and therefore enables the tuning of the hole effective masses and band gaps. These results present an important advance towards the understanding of flexoelectric and electronic properties of hydrogen and fluorine functionalized graphene nanoribbons, which can have important implications for flexible electronic applications. (C) 2020 Elsevier Ltd. All rights reserved.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000598371500058	Publication Date	2020-09-17
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0008-6223	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	6.337	Times cited	11	Open Access	OpenAccess
	Notes	; The computational resources and services used for the first-principles calculations in this work were provided by the VSC (Flemish Supercomputer Center), funded by the Flemish Science Foundation (FWO-VI). T. P. is supported by a postdoctoral research fellowship from BOF-UAntwerpen. ;			Approved	Most recent IF: 6.337
	Call Number	UA @ admin @ c:irua:175014			Serial	6700
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	Author	Lavor, I.R.; da Costa, D.R.; Covaci, L.; Milošević, M.V.; Peeters, F.M.; Chaves, A.
	Title	Zitterbewegung of moiré excitons in twisted MoS₂/WSe₂ heterobilayers			Type	A1 Journal article
	Year	2021	Publication	Physical review letters	Abbreviated Journal
	Volume	127	Issue	10	Pages	106801
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	The moire pattern observed in stacked noncommensurate crystal lattices, such as heterobilayers of transition metal dichalcogenides, produces a periodic modulation of their band gap. Excitons subjected to this potential landscape exhibit a band structure that gives rise to a quasiparticle dubbed the moire exciton. In the case of MoS2/WSe2 heterobilayers, the moire trapping potential has honeycomb symmetry and, consequently, the moire exciton band structure is the same as that of a Dirac-Weyl fermion, whose mass can be further tuned down to zero with a perpendicularly applied field. Here we show that, analogously to other Dirac-like particles, the moire exciton exhibits a trembling motion, also known as Zitterbewegung, whose long timescales are compatible with current experimental techniques for exciton dynamics. This promotes the study of the dynamics of moire excitons in van der Waals heterostructures as an advantageous solid-state platform to probe Zitterbewegung, broadly tunable by gating and interlayer twist angle.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000692200800020	Publication Date	2021-08-31
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	1079-7114	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor		Times cited	4	Open Access	OpenAccess
	Notes				Approved	Most recent IF: NA
	Call Number	UA @ admin @ c:irua:181599			Serial	6896
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	Author	Chaves, A.; Covaci, L.; Peeters, F.M.; Milošević, M.V.
	Title	Topologically protected moiré exciton at a twist-boundary in a van der Waals heterostructure			Type	A1 Journal article
	Year	2022	Publication	2D materials	Abbreviated Journal	2D Mater
	Volume	9	Issue	2	Pages	025012
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	A twin boundary in one of the layers of a twisted van der Waals heterostructure separates regions with near opposite inter-layer twist angles. In a MoS<sub>2</sub>/WSe<sub>2</sub>bilayer, the regions with<inline-formula><tex-math><?CDATA $Rh^h$?></tex-math><math overflow=“scroll”><msubsup><mi>R</mi><mi>h</mi><mi>h</mi></msubsup></math><inline-graphic href=“tdmac529dieqn1.gif” type=“simple” /></inline-formula>and<inline-formula><tex-math><?CDATA $Rh^X$?></tex-math><math overflow=“scroll”><msubsup><mi>R</mi><mi>h</mi><mi>X</mi></msubsup></math><inline-graphic href=“tdmac529dieqn2.gif” type=“simple” /></inline-formula>stacking registry that defined the sub-lattices of the moiré honeycomb pattern would be mirror-reflected across such a twist boundary. In that case, we demonstrate that topologically protected chiral moiré exciton states are confined at the twist boundary. These are one-dimensional and uni-directional excitons with opposite velocities for excitons composed by electronic states with opposite valley/spin character, enabling intrinsic, guided, and far reaching valley-polarized exciton currents.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000760518100001	Publication Date	2022-04-01
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2053-1583	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	5.5	Times cited		Open Access	OpenAccess
	Notes	Fonds Wetenschappelijk Onderzoek; Conselho Nacional de Desenvolvimento Científico e Tecnológico, PQ ;			Approved	Most recent IF: 5.5
	Call Number	CMT @ cmt @c:irua:187124			Serial	7046
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	Author	Linard, F.J.A.; Moura, V.N.; Covaci, L.; Milošević, M.V.; Chaves, A.
	Title	Wave-packet scattering at a normal-superconductor interface in two-dimensional materials : a generalized theoretical approach			Type	A1 Journal article
	Year	2023	Publication	Physical review B	Abbreviated Journal
	Volume	107	Issue	16	Pages	165306-165309
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	A wave-packet time evolution method, based on the split-operator technique, is developed to investigate the scattering of quasiparticles at a normal-superconductor interface of arbitrary profile and shape. As a practical application, we consider a system where low-energy electrons can be described as Dirac particles, which is the case for most two-dimensional materials, such as graphene and transition-metal dichalcogenides. However, the method is easily adapted for other cases such as electrons in few-layer black phosphorus or any Schrodinger quasiparticles within the effective mass approximation in semiconductors. We employ the method to revisit Andreev reflection in mono-, bi-, and trilayer graphene, where specular-and retro-reflection cases are observed for electrons scattered by a steplike superconducting region. The effect of opening a zero-gap channel across the superconducting region on the electron and hole scattering is also addressed, as an example of the versatility of the technique proposed here.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos	000974675700006	Publication Date	2023-04-14
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	2469-9969; 2469-9950	ISBN		Additional Links	UA library record; WoS full record; WoS citing articles
	Impact Factor	3.7	Times cited		Open Access	OpenAccess
	Notes				Approved	Most recent IF: 3.7; 2023 IF: 3.836
	Call Number	UA @ admin @ c:irua:196709			Serial	8954
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	Author	Jorissen, B.; Covaci, L.; Partoens, B.
	Title	Comparative analysis of tight-binding models for transition metal dichalcogenides			Type	A1 Journal article
	Year	2024	Publication	SciPost physics core	Abbreviated Journal
	Volume	7	Issue	1	Pages	004-30
	Keywords	A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT)
	Abstract	We provide a comprehensive analysis of the prominent tight-binding (TB) models for transition metal dichalcogenides (TMDs) available in the literature. We inspect the construction of these TB models, discuss their parameterization used and conduct a thorough comparison of their effectiveness in capturing important electronic properties. Based on these insights, we propose a novel TB model for TMDs designed for enhanced computational efficiency. Utilizing MoS2 as a representative case, we explain why specific models offer a more accurate description. Our primary aim is to assist researchers in choosing the most appropriate TB model for their calculations on TMDs.
	Address
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language		Wos		Publication Date	2024-02-06
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN		ISBN		Additional Links	UA library record
	Impact Factor		Times cited		Open Access	Not_Open_Access
	Notes				Approved	no
	Call Number	UA @ admin @ c:irua:202983			Serial	9012
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	Author	Covaci, L.; Berciu, M.
	Title	Survival of the Dirac points in rippled graphene			Type	A1 Journal article
	Year	2008	Publication	Physical Review Letters	Abbreviated Journal	Phys Rev Lett
	Volume	100	Issue	25	Pages	256405
	Keywords	A1 Journal article; Electron Microscopy for Materials Science (EMAT);
	Abstract	We study the effects of the rippling of a graphene sheet on quasiparticle dispersion. This is achieved using a generalization to the honeycomb lattice of the momentum average approximation, which is accurate for all coupling strengths and at all energies. We show that even though the position of the Dirac points may move and the Fermi speed can be renormalized significantly, quasiparticles with very long lifetimes survive near the Dirac points even for very strong couplings.
	Address	Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z1
	Corporate Author				Thesis
	Publisher		Place of Publication		Editor
	Language	English	Wos	000257230500047	Publication Date	2008-06-26
	Series Editor		Series Title		Abbreviated Series Title
	Series Volume		Series Issue		Edition
	ISSN	0031-9007	ISBN		Additional Links
	Impact Factor	8.462	Times cited	15	Open Access
	Notes				Approved	Most recent IF: 8.462; 2008 IF: 7.180
	Call Number	UA @ lucian @			Serial	4010
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