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Author Xiao, H.; Zhang, Z.; Xu, W.; Wang, Q.; Xiao, Y.; Ding, L.; Huang, J.; Li, H.; He, B.; Peeters, F.M.
Title Terahertz optoelectronic properties of synthetic single crystal diamond Type A1 Journal article
Year 2023 Publication Diamond and related materials Abbreviated Journal
Volume 139 Issue Pages 110266-110268
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A systematic investigation is undertaken for studying the optoelectronic properties of single crystal diamond (SCD) grown by microwave plasma chemical vapor deposition (MPCVD). It is indicated that, without intentional doping and surface treatment during the sample growth, the terahertz (THz) optical conduction in SCD is mainly affected by surface H-terminations, -OH-, O- and N-based functional groups. By using THz time-domain spectroscopy (TDS), we measure the transmittance, the complex dielectric constant and optical conductivity σ(ω) of SCD. We find that SCD does not show typical semiconductor characteristics in THz regime, where σ(ω) cannot be described rightly by the conventional Drude formula. Via fitting the real and imaginary parts of σ(ω) to the Drude-Smith formula, the ratio of the average carrier density to the effective electron mass γ = ne/m*, the electronic relaxation time τ and the electronic backscattering or localization factor can be determined optically. The temperature dependence of these parameters is examined. From the temperature dependence of γ, a metallic to semiconductor transition is observed at about T = 10 K. The temperature dependence of τ is mainly induced by electron coupling with acoustic-phonons and there is a significant effect of photon-induced electron backscattering or localization in SCD. This work demonstrates that THz TDS is a powerful technique in studying SCD which contains H-, N- and O-based bonds and has low electron density and high dc resistivity. The results obtained from this study can benefit us to gain an in-depth understanding of SCD and may provide new guidance for the application of SCD as electronic, optical and optoelectronic materials.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date 2023-08-02
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0925-9635 ISBN Additional Links UA library record
Impact Factor 4.1 Times cited (down) Open Access
Notes Approved Most recent IF: 4.1; 2023 IF: 2.561
Call Number UA @ admin @ c:irua:200920 Serial 9103
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Author Shafiei, M.; Fazileh, F.; Peeters, F.M.; Milošević, M.V.
Title Floquet engineering of axion and high-Chern number phases in a topological insulator under illumination Type A1 Journal article
Year 2024 Publication SciPost Physics Core Abbreviated Journal
Volume 7 Issue 7 Pages 024-16
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Quantum anomalous Hall, high-Chern number, and axion phases in topological insulators are characterized by its Chern invariant C (respectively, C = 1, integer C > 1, and C = 0 with half-quantized Hall conductance of opposite signs on top and bottom surfaces). They are of recent interest because of novel fundamental physics and prospective applications, but identifying and controlling these phases has been challenging in practice. Here we show that these states can be created and switched between in thin films of Bi2Se3 by Floquet engineering, using irradiation by circularly polarized light. We present the calculated phase diagrams of encountered topological phases in Bi2Se3, as a function of wavelength and amplitude of light, as well as sample thickness, after properly taking into account the penetration depth of light and the variation of the gap in the surface states. These findings open pathways towards energy-efficient optoelectronics, advanced sensing, quantum information processing and metrology.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001217885300001 Publication Date 2024-05-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record; WoS full record
Impact Factor Times cited (down) Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:205972 Serial 9151
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Author Nazar, N.D.; Peeters, F.M.; Costa Filho, R.N.; Vazifehshenas, T.
Title 8-pmmn borophene : edge states in competition with Landau levels and local vacancy states Type A1 Journal article
Year 2024 Publication Physical chemistry, chemical physics Abbreviated Journal
Volume 26 Issue 22 Pages 16153-16159
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The tight-binding method is used to investigate the electronic and magnetic properties of borophene nano-ribbons (BNRs) in the presence of a perpendicular magnetic field. Most BNRs exhibit metallic characteristics due to edge bands. Additionally, the appearance of Landau levels (LLs) is strongly influenced by the edge states, contrasting with the sheet platform which produces distinct LLs. We also investigated single atomic vacancy disorders in BNRs and observed localized vacancy states (LVSs) resulting from atomic disorder. Both LVSs and LLs are influenced by the edge states, underscoring that the electronic and magnetic properties of BNRs are strongly edge-dependent. This aspect is crucial for consideration in experimental, theoretical, and computational studies.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001230536600001 Publication Date 2024-05-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1463-9076; 1463-9084 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.3 Times cited (down) Open Access
Notes Approved Most recent IF: 3.3; 2024 IF: 4.123
Call Number UA @ admin @ c:irua:206599 Serial 9274
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Author Li, Q.N.; Vasilopoulos, P.; Peeters, F.M.; Xu, W.; Xiao, Y.M.; Milošević, M.V.
Title Collective excitations in three-dimensional Dirac systems Type A1 Journal article
Year 2024 Publication Physical review B Abbreviated Journal
Volume 109 Issue 11 Pages 115123-115129
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We provide the plasmon spectrum and related properties of the three-dimensional (3D) Dirac semimetals Na 3 Bi and Cd 3 As 2 based on the random -phase approximation. The necessary one -electron eigenvalues and eigenfunctions are obtained from an effective k <middle dot> p Hamiltonian. Below the energy at which the velocity v z along the k z axis vanishes, the density of states differs drastically from that of a 3D electron gas (3DEG) or graphene. The dispersion relation is anisotropic for wave vectors parallel ( q ) and perpendicular ( q z ) to the ( x , y ) plane and is markedly different than that of graphene or a 3DEG. The same holds for the energy -loss function. Both depend sensitively on the position of the Fermi energy E F relative to the region of the Berry curvature of the bands. For E F below the energy at which v z vanishes, the range of the relevant wave vectors q and q z shrinks, for q z by about one order of magnitude.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001235353700005 Publication Date 2024-03-13
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
Impact Factor 3.7 Times cited (down) Open Access
Notes Approved Most recent IF: 3.7; 2024 IF: 3.836
Call Number UA @ admin @ c:irua:206669 Serial 9278
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Author Song, Y.; Chen, M.; Xie, X.; Liu, X.; Li, J.; Peeters, F.M.; Li, L.
Title Hydrogenation-controlled band engineering of dumbbell graphene Type A1 Journal article
Year 2024 Publication Nano energy Abbreviated Journal
Volume 127 Issue Pages 109763-15
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract The stability of the dumbbell structure has been confirmed by previous theory and experiment. Based on firstprinciples calculations, we proposed hexagonal dumbbell graphene (HDB C10) and rectangular dumbbell graphene (RDB C10) monolayers containing periodically raised C (CR) atoms. They turn out to have high mobility semiconductor properties. By adsorbing H atoms on these CR atoms, their band structures can be widely tuned from semiconductor to semimetal. When considering adsorption of two/four H atoms on the unit cell of the dumbbell structure, the bandgap can be increased, and isolated flat band structures can be obtained by further adding or removing H atoms. Remarkably, two different Dirac band structures can be found in the HDB/RDB C10H2-I monolayers. The HDB C10H2-I shows a Dirac cone with isotropic Fermi velocities, while the RDB C10H2-I monolayer exhibits a quasi-one-dimensional Dirac nodal line with varying Fermi velocities along the XS path. Tight-binding (TB) models are constructed including nearest neighbor (NN) and next NN hopping in order to understand our DFT results. These TB models are related to the Su-Schrieffer-Heeger model, and are able to explain the tunable topological properties of the RDB C10H2-I monolayer. They not only are able to explain the different kinds of Fermi velocity, but also can predict the emergence of topological edge states, providing a good platform for research on Dirac fermions. The HDB/RDB C10 monolayer exhibits more freedom of tunable band structures and more stable hydrogen storage capacity, making it superior to graphene. Finally, possible experimental synthesis paths of these DB monolayers are provided.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001244362400001 Publication Date 2024-05-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2211-2855 ISBN Additional Links UA library record; WoS full record
Impact Factor 17.6 Times cited (down) Open Access
Notes Approved Most recent IF: 17.6; 2024 IF: 12.343
Call Number UA @ admin @ c:irua:206621 Serial 9296
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Author Cheng, X.; Xu, W.; Wen, H.; Zhang, J.; Zhang, H.; Li, H.; Peeters, F.M.
Title Key electronic parameters of 2H-stacking bilayer MoS₂ on sapphire substrate determined by terahertz magneto-optical measurement in Faraday geometry Type A1 Journal article
Year 2024 Publication Frontiers of physics Abbreviated Journal
Volume 19 Issue 6 Pages 63204-63209
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Bilayer (BL) transition metal dichalcogenides (TMDs) are important materials in valleytronics and twistronics. Here we study terahertz (THz) magneto-optical (MO) properties of n-type 2H-stacking BL molybdenum sulfide (MoS2) on sapphire substrate grown by chemical vapor deposition. The AFM, Raman spectroscopy and photoluminescence are used for characterization of the samples. Applying THz time-domain spectroscopy (TDS), in combination with polarization test and the presence of magnetic field in Faraday geometry, THz MO transmissions through the sample are measured from 0 to 8 T at 80 K. The complex right- and left-handed circular MO conductivities for 2H-stacking BL MoS2 are obtained. Through fitting the experimental results with theoretical formula of MO conductivities for an electron gas, generalized by us previously through the inclusion of photon-induced electronic backscattering effect, we are able to determine magneto-optically the key electronic parameters of BL MoS2, such as the electron density n(e), the electronic relaxation time tau, the electronic localization factor c and, particularly, the effective electron mass m* around Q-point in between the K- and Gamma-point in the electronic band structure. The dependence of these parameters upon magnetic field is examined and analyzed. This is a pioneering experimental work to measure m* around the Q-point in 2H-stacking BL MoS2 and the experimental value is very close to that obtained theoretically. We find that n(e)/tau/ divided by c divided by /m* in 2H-stacking BL MoS2 decreases/increases/decreases/increases with increasing magnetic field. The results obtained from this study can be benefit to us in gaining an in-depth understanding of the electronic and optoelectronic properties of BL TMD systems.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=brocade2&SrcAuth=WosAPI&KeyUT=WOS:001271 Publication Date 2024-07-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2095-0462; 2095-0470 ISBN Additional Links UA library record; WoS full record
Impact Factor 7.5 Times cited (down) Open Access
Notes Approved Most recent IF: 7.5; 2024 IF: 2.579
Call Number UA @ admin @ c:irua:207600 Serial 9300
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Author Liu, J.; Xu, W.; Xiao, Y.M.; Ding, L.; Li, H.W.; Van Duppen, B.; Milošević, M.V.; Peeters, F.M.
Title Longitudinal and transverse mobilities of n-type monolayer transition metal dichalcogenides in the presence of proximity-induced interactions at low temperature Type A1 Journal article
Year 2024 Publication Physical review B Abbreviated Journal
Volume 109 Issue 19 Pages 195418-14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We present a detailed theoretical investigation on the electronic transport properties of n-type monolayer (ML) transition metal dichalcogenides (TMDs) at low temperature in the presence of proximity-induced interactions such as Rashba spin-orbit coupling (RSOC) and the exchange interaction. The electronic band structure is calculated by solving the Schr & ouml;dinger equation with a k <middle dot> p Hamiltonian, and the electric screening induced by electron-electron interaction is evaluated under a standard random phase approximation approach. In particular, the longitudinal and transverse or Hall mobilities are calculated by using a momentum-balance equation derived from a semiclassical Boltzmann equation, where the electron-impurity interaction is considered as the principal scattering center at low temperature. The obtained results show that the RSOC can induce the in-plane spin components for spin-split subbands in different valleys, while the exchange interaction can lift the energy degeneracy for electrons in different valleys. The opposite signs of Berry curvatures in the two valleys would introduce opposite directions of Lorentz force on valley electrons. As a result, the transverse currents from nondegenerate valleys can no longer be canceled out so that the transverse current or Hall mobility can be observed. Interestingly, we find that at a fixed effective Zeeman field, the lowest spin-split conduction subband in ML-TMDs can be tuned from one in the K'-valley to one in the K-valley by varying the Rashba parameter. The occupation of electrons in different valleys also varies with changing carrier density. Therefore, we can change the magnitude and direction of the Hall current by varying the Rashba parameter, effective Zeeman field, and carrier density by, e.g., the presence of a ferromagnetic substrate and/or applying a gate voltage. By taking the ML-MoS2 as an example, these effects are demonstrated and examined. The important and interesting theoretical findings can be beneficial to experimental observation of the valleytronic effect and to gaining an in-depth understanding of the ML-TMD systems in the presence of proximity-induced interactions.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001237245700001 Publication Date 2024-05-08
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
Impact Factor 3.7 Times cited (down) Open Access
Notes Approved Most recent IF: 3.7; 2024 IF: 3.836
Call Number UA @ admin @ c:irua:206596 Serial 9302
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Author Li, Y.; Xiao, Y.M.; Xu, W.; Ding, L.; Milošević, M.V.; Peeters, F.M.
Title Magneto-optical conductivity of monolayer transition metal dichalcogenides in the presence of proximity-induced exchange interaction and external electrical field Type A1 Journal article
Year 2024 Publication Physical review B Abbreviated Journal
Volume 109 Issue 16 Pages 165441-14
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We theoretically investigate the magneto-optical (MO) properties of monolayer (ML) transition metal dichalcogenides (TMDs) in the presence of external electrical and quantizing magnetic fields and of the proximity-induced exchange interaction. The corresponding Landau Level (LL) structure is studied by solving the Schr & ouml;dinger equation and the spin polarization in ML-TMDs under the action of the magnetic field is evaluated. The impact of trigonal warping on LLs and MO absorption is examined. Furthermore, the longitudinal MO conductivity is calculated through the dynamical dielectric function under the standard random-phase approximation (RPA) with the Kubo formula. We take ML-MoS 2 as an example to examine the effects of proximity-induced exchange interaction, external electrical and magnetic fields on the MO conductivity induced via intra- and interband electronic transitions among the LLs. For intraband electronic transitions within the conduction or valence bands, we can observe two absorption peaks in terahertz (THz) frequency range. While the interband electronic transitions between conduction and valence LLs show a series of absorption peaks in the visible range. We find that the proximity-induced exchange interaction, the carrier density, the strengths of the external electrical and magnetic fields can effectively modulate the positions of the absorption peaks and the shapes of the MO absorption spectra. The results obtained from this study can benefit to an in-depth understanding of the MO properties of ML-TMDs which can be potentially applied for magneto-optic, spintronic, and valleytronic devices working in visible to THz frequency bandwidths.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001231884200004 Publication Date 2024-04-26
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 3.7 Times cited (down) Open Access
Notes Approved Most recent IF: 3.7; 2024 IF: 3.836
Call Number UA @ admin @ c:irua:206589 Serial 9305
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Author Tian, X.; Xie, X.; Li, J.; Kong, X.; Gong, W.-J.; Peeters, F.M.; Li, L.
Title Multiferroic ScLaX₂ (X = P, As, and Sb) monolayers : bidirectional negative Poisson's ratio effects and phase transformations driven by rare-earth (main-group) elements Type A1 Journal article
Year 2024 Publication Physical review materials Abbreviated Journal
Volume 8 Issue 8 Pages 084407-84411
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The combination of auxetic property, ferroelasticity, and ferroelectricity in two-dimensional materials offers new avenues for next-generation multifunctional devices. However, two-dimensional materials that simultaneously exhibit those properties are rarely reported. Here, we present a class of two-dimensional Janus-like structures ScLaX2 X 2 (X X = P, As, and Sb) with a rectangular lattice based on first-principles calculations. We predict that those ScLaX2 X 2 monolayers are stable semiconductors with both intrinsic in-plane and out-of-plane auxetic properties, showing a bidirectional negative Poisson's ratio effect. The value of the out-of-plane negative Poisson's ratio effect can reach – 2.28 /- 3.06 /- 3.89. By applying uniaxial strain engineering, two transition paths can be found, including the VA main group element path and the rare-earth metal element path, corresponding to the ferroelastic and the multiferroic (ferroelastic and ferroelectric) phase transition, respectively. For the ScLaSb2 2 monolayer, the external force field can not only control the ferroelastic phase transition, but it can also lead to the reversal of the out-of-plane polarization, exhibiting potential multiferroicity. The coupling between the bidirectional negative Poisson's ratio effect and multiferroicity makes the ScLaX2 X 2 monolayers promising for future device applications.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=brocade2&SrcAuth=WosAPI&KeyUT=WOS:001293 Publication Date 2024-08-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2475-9953 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.4 Times cited (down) Open Access
Notes Approved Most recent IF: 3.4; 2024 IF: NA
Call Number UA @ admin @ c:irua:207592 Serial 9306
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Author Shafiei, M.; Fazileh, F.; Peeters, F.M.; Milošević, M.V.
Title Tuning the quantum phase transition of an ultrathin magnetic topological insulator Type A1 Journal article
Year 2024 Publication Physical review materials Abbreviated Journal
Volume 8 Issue 7 Pages 074201-74208
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract We explore the effect of thickness, magnetization direction, strain, and gating on the topological quantum phase transition of a thin-film magnetic topological insulator. Reducing the film thickness to the ultrathin regime couples the edge states on the two surfaces, opening a gap known as the hybridization gap, and causing a phase transition from a topological insulator to a normal insulator (NI). An out-of-plane/in-plane magnetization of size proportional to the hybridization gap triggers a phase transition from a normal insulator state to a quantum anomalous Hall (QAH)/semimetal state. A magnetization tilt by angle 0 from the out-of-plane axis influences the topological phase transition in a way that for sufficiently large 0, no phase transition from NI to QAH can be observed regardless of the sample thickness or magnetization, and for 0 close to pi /2 the system transits to a semimetal phase. Furthermore, we demonstrate that compressive/tensile strain can be used to decrease/increase the magnetization threshold for the topological phase transition. Finally, we reveal the effect of a vertical potential acting on the film, be it due to the substrate or applied gating, which breaks inversion symmetry and raises the magnetization threshold for the transition from NI to QAH state.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=brocade2&SrcAuth=WosAPI&KeyUT=WOS:001281 Publication Date 2024-07-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2475-9953 ISBN Additional Links UA library record; WoS full record
Impact Factor 3.4 Times cited (down) Open Access
Notes Approved Most recent IF: 3.4; 2024 IF: NA
Call Number UA @ admin @ c:irua:207598 Serial 9324
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Author Lavor, I.R.; Tao, Z.H.; Dong, H.M.; Chaves, A.; Peeters, F.M.; Milošević, M.V.
Title Ultrasensitive acoustic graphene plasmons in a graphene-transition metal dichalcogenide heterostructure : strong plasmon-phonon coupling and wavelength sensitivity enhanced by a metal screen Type A1 Journal article
Year 2024 Publication Carbon Abbreviated Journal
Volume 228 Issue Pages 119401-119409
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Acoustic plasmons in graphene exhibit strong confinement induced by a proximate metal surface and hybridize with phonons of transition metal dichalcogenides (TMDs) when these materials are combined in a van der Waals heterostructure, thus forming screened graphene plasmon-phonon polaritons (SGPPPs), a type of acoustic mode. While SGPPPs are shown to be very sensitive to the dielectric properties of the environment, enhancing the SGPPPs coupling strength in realistic heterostructures is still challenging. Here we employ the quantum electrostatic heterostructure model, which builds upon the density functional theory calculations for monolayers, to show that the use of a metal as a substrate for graphene-TMD heterostructures (i) vigorously enhances the coupling strength between acoustic plasmons and the TMD phonons, and (ii) markedly improves the sensitivity of the plasmon wavelength on the structural details of the host platform in real space, thus allowing one to use the effect of environmental screening on acoustic plasmons to probe the structure and composition of a van der Waals heterostructure down to the monolayer resolution.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos https://www.webofscience.com/api/gateway?GWVersion=2&SrcApp=brocade2&SrcAuth=WosAPI&KeyUT=WOS:001267 Publication Date 2024-07-02
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 full record
Impact Factor 10.9 Times cited (down) Open Access
Notes Approved Most recent IF: 10.9; 2024 IF: 6.337
Call Number UA @ admin @ c:irua:207077 Serial 9325
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