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Author Sarikurt, S.; Çakir, D.; Keceli, M.; Sevik, C.
Title The influence of surface functionalization on thermal transport and thermoelectric properties of MXene monolayers Type A1 Journal article
Year 2018 Publication Nanoscale Abbreviated Journal
Volume 10 Issue 18 Pages 8859-8868
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract The newest members of a two-dimensional material family, involving transition metal carbides and nitrides (called MXenes), have garnered increasing attention due to their tunable electronic and thermal properties depending on the chemical composition and functionalization. This flexibility can be exploited to fabricate efficient electrochemical energy storage (batteries) and energy conversion (thermoelectric) devices. In this study, we calculated the Seebeck coefficients and lattice thermal conductivity values of oxygen terminated M2CO2 (where M = Ti, Zr, Hf, Sc) monolayer MXene crystals in two different functionalization configurations (model-II (MD-II) and model-III (MD-III)), using density functional theory and Boltzmann transport theory. We estimated the thermoelectric figure-of-merit, zT, of these materials by two different approaches, as well. First of all, we found that the structural model (i.e. adsorption site of oxygen atom on the surface of MXene) has a paramount impact on the electronic and thermoelectric properties of MXene crystals, which can be exploited to engineer the thermoelectric properties of these materials. The lattice thermal conductivity kappa(l), Seebeck coefficient and zT values may vary by 40% depending on the structural model. The MD-III configuration always has the larger band gap, Seebeck coefficient and zT, and smaller kappa(l) as compared to the MD-II structure due to a larger band gap, highly flat valence band and reduced crystal symmetry in the former. The MD-III configuration of Ti2CO2 and Zr2CO2 has the lowest kappa(l) as compared to the same configuration of Hf2CO2 and Sc2CO2. Among all the considered structures, the MD-II configuration of Hf2CO2 has the highest kappa(l), and Ti2CO2 and Zr2CO2 in the MD-III configuration have the lowest kappa(l). For instance, while the band gap of the MD-II configuration of Ti2CO2 is 0.26 eV, it becomes 0.69 eV in MD-III. The zT(max) value may reach up to 1.1 depending on the structural model of MXene.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000432096400055 Publication Date 2018-04-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2040-3364; 2040-3372 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:193788 Serial 8654
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Author Xiao, Y.
Title Theoretical study of the optoelectronic properties of new type 2DEG materials : multilayer graphene and monolayer MoS2 Type Doctoral thesis
Year 2017 Publication Abbreviated Journal
Volume Issue Pages 144 p.
Keywords Doctoral thesis; Condensed Matter Theory (CMT)
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:144948 Serial 8661
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Author Kandemir, A.; Ozden, A.; Cagin, T.; Sevik, C.
Title Thermal conductivity engineering of bulk and one-dimensional Si-Ge nanoarchitectures Type A1 Journal article
Year 2017 Publication Science and technology of advanced materials Abbreviated Journal
Volume 18 Issue 1 Pages 187-196
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Various theoretical and experimental methods are utilized to investigate the thermal conductivity of nanostructured materials; this is a critical parameter to increase performance of thermoelectric devices. Among these methods, equilibrium molecular dynamics (EMD) is an accurate technique to predict lattice thermal conductivity. In this study, by means of systematic EMD simulations, thermal conductivity of bulk Si-Ge structures (pristine, alloy and superlattice) and their nanostructured one dimensional forms with square and circular cross-section geometries (asymmetric and symmetric) are calculated for different crystallographic directions. A comprehensive temperature analysis is evaluated for selected structures as well. The results show that one-dimensional structures are superior candidates in terms of their low lattice thermal conductivity and thermal conductivity tunability by nanostructuring, such as by diameter modulation, interface roughness, periodicity and number of interfaces. We find that thermal conductivity decreases with smaller diameters or cross section areas. Furthermore, interface roughness decreases thermal conductivity with a profound impact. Moreover, we predicted that there is a specific periodicity that gives minimum thermal conductivity in symmetric superlattice structures. The decreasing thermal conductivity is due to the reducing phonon movement in the system due to the effect of the number of interfaces that determine regimes of ballistic and wave transport phenomena. In some nanostructures, such as nanowire superlattices, thermal conductivity of the Si/Ge system can be reduced to nearly twice that of an amorphous silicon thermal conductivity. Additionally, it is found that one crystal orientation, <100>, is better than the <111> crystal orientation in one-dimensional and bulk SiGe systems. Our results clearly point out the importance of lattice thermal conductivity engineering in bulk and nanostructures to produce high-performance thermoelectric materials.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000405949800001 Publication Date 2017-03-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1468-6996; 1878-5514 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:193772 Serial 8662
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Author Taghizadeh Sisakht, E.
Title Tight-binding investigation of the electronic properties of phosphorene and phosphorene nanoribbons Type Doctoral thesis
Year 2019 Publication Abbreviated Journal
Volume Issue Pages 150 p.
Keywords Doctoral thesis; Condensed Matter Theory (CMT)
Abstract abstract not available
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:166195 Serial 8670
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Author Nakhaee, M.
Title Tight-binding model for two-dimensional materials Type Doctoral thesis
Year 2020 Publication Abbreviated Journal
Volume Issue Pages 139 p.
Keywords Doctoral thesis; Condensed Matter Theory (CMT)
Abstract abstract not available
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:166134 Serial 8671
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Author Mobaraki, A.; Kandemir, A.; Yapicioglu, H.; Gulseren, O.; Sevik, C.
Title Validation of inter-atomic potential for WS2 and WSe2 crystals through assessment of thermal transport properties Type A1 Journal article
Year 2018 Publication Computational materials science Abbreviated Journal
Volume 144 Issue Pages 92-98
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract In recent years, transition metal dichalcogenides (TMDs) displaying astonishing properties are emerged as a new class of two-dimensional layered materials. The understanding and characterization of thermal transport in these materials are crucial for efficient engineering of 2D TMD materials for applications such as thermoelectric devices or overcoming general overheating issues. In this work, we obtain accurate Stillinger-Weber type empirical potential parameter sets for single-layer WS2 and WSe2 crystals by utilizing particle swarm optimization, a stochastic search algorithm. For both systems, our results are quite consistent with first-principles calculations in terms of bond distances, lattice parameters, elastic constants and vibrational properties. Using the generated potentials, we investigate the effect of temperature on phonon energies and phonon linewidth by employing spectral energy density analysis. We compare the calculated frequency shift with respect to temperature with corresponding experimental data, clearly demonstrating the accuracy of the generated inter-atomic potentials in this study. Also, we evaluate the lattice thermal conductivities of these materials by means of classical molecular dynamics simulations. The predicted thermal properties are in very good agreement with the ones calculated from first-principles. (C) 2017 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000424902300013 Publication Date 2017-12-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0927-0256 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:193774 Serial 8729
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Author da Costa, D.R.; Chaves, A.; Farias, G.A.; Peeters, F.M.
Title Valley filtering in graphene due to substrate-induced mass potential Type A1 Journal article
Year 2017 Publication Journal of physics : condensed matter Abbreviated Journal
Volume 29 Issue 21 Pages 215502
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract The interaction of monolayer graphene with specific substrates may break its sublattice symmetry and results in unidirectional chiral states with opposite group velocities in the different Dirac cones (Zarenia et al 2012 Phys. Rev. B 86 085451). Taking advantage of this feature, we propose a valley filter based on a transversal mass kink for low energy electrons in graphene, which is obtained by assuming a defect region in the substrate that provides a change in the sign of the substrate-induced mass and thus creates a non-biased channel, perpendicular to the kink, for electron motion. By solving the time-dependent Schrodinger equation for the tight-binding Hamiltonian, we investigate the time evolution of a Gaussian wave packet propagating through such a system and obtain the transport properties of this graphene-based substrate-induced quantum point contact. Our results demonstrate that efficient valley filtering can be obtained, provided: (i) the electron energy is sufficiently low, i.e. with electrons belonging mostly to the lowest sub-band of the channel, and (ii) the channel length (width) is sufficiently long (narrow). Moreover, even though the transmission probabilities for each valley are significantly affected by impurities and defects in the channel region, the valley polarization in this system is shown to be robust against their presence.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000400092700002 Publication Date 2017-04-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) Times cited 15 Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:152636 Serial 8730
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Author Kenawy, A.; Magnus, W.; Milošević, M.V.; Sorée, B.
Title Voltage-controlled superconducting magnetic memory Type A1 Journal article
Year 2019 Publication AIP advances T2 – 64th Annual Conference on Magnetism and Magnetic Materials (MMM), NOV 04-08, 2019, Las Vegas, NV Abbreviated Journal
Volume 9 Issue 12 Pages 125223
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract Over the past few decades, superconducting circuits have been used to realize various novel electronic devices such as quantum bits, SQUIDs, parametric amplifiers, etc. One domain, however, where superconducting circuits fall short is information storage. Superconducting memories are based on the quantization of magnetic flux in superconducting loops. Standard implementations store information as magnetic flux quanta in a superconducting loop interrupted by two Josephson junctions (i.e., a SQUID). However, due to the large inductance required, the size of the SQUID loop cannot be scaled below several micrometers, resulting in low-density memory chips. Here, we propose a scalable memory consisting of a voltage-biased superconducting ring threaded by a half-quantum flux bias. By numerically solving the time-dependent Ginzburg-Landau equations, we show that applying a time-dependent bias voltage in the microwave range constitutes a writing mechanism to change the number of stored flux quanta within the ring. Since the proposed device does not require a large loop inductance, it can be scaled down, enabling a high-density memory technology. (C) 2019 Author(s).
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000515525300002 Publication Date 2019-12-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2158-3226 ISBN Additional Links UA library record; WoS full record
Impact Factor (down) Times cited Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:167551 Serial 8740
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Author Leenaerts, O.; Partoens, B.; Peeters, F.M.; Volodin, A.; van Haesendonck, C.
Title The work function of few-layer graphene Type A1 Journal article
Year 2017 Publication Journal of physics : condensed matter Abbreviated Journal
Volume 29 Issue 3 Pages 035003
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract A theoretical and experimental study of the work function of few-layer graphene is reported. The influence of the number of layers on the work function is investigated in the presence of a substrate, a molecular dipole layer, and combinations of the two. The work function of few-layer graphene is almost independent of the number of layers with only a difference between monolayer and multilayer graphene of about 60 meV. In the presence of a charge-donating substrate the charge distribution is found to decay exponentially away from the substrate and this is directly reflected in the work function of few-layer graphene. A dipole layer changes the work function only when placed in between the substrate and few-layer graphene through a change of the charge transfer between the two.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000425250600002 Publication Date 2016-11-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0953-8984 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) Times cited 61 Open Access
Notes Approved no
Call Number UA @ admin @ c:irua:164938 Serial 8760
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Author Espinosa, I.M.P.; Karaaslan, Y.; Sevik, C.; Martini, A.
Title Atomistic model of the anisotropic response of ortho-Mo₂C to indentation Type A1 Journal article
Year 2023 Publication AIP advances Abbreviated Journal
Volume 13 Issue 6 Pages 065125-65127
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract Molybdenum carbide has various applications for which studying the material using classical molecular dynamics simulations would be valuable. Here, we develop an empirical potential within the Tersoff formalism using particle swarm optimization for the orthorhombic phase of Mo2C. The developed potential is shown to predict lattice constants, elastic properties, and equation of state results that are consistent with current and previously reported results from experiments and first principles calculations. We demonstrate the potential with simulations of indentation using multiple indenter sizes that load and unload in three different directions relative to the crystallographic lattice of orthorhombic Mo2C. Direction-dependent force-displacement trends are analyzed and explained in terms of the spatial distributions of stress and strain within the material during indentation. This study reveals the anisotropic elasticity of orthorhombic Mo2C and, more generally, provides researchers with a new empirical potential that can be used to explore the properties and behavior of the material going forward.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001016472500005 Publication Date 2023-06-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2158-3226 ISBN Additional Links UA library record; WoS full record
Impact Factor (down) Times cited Open Access OpenAccess
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:198333 Serial 8834
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Author Vizarim, N.P.
Title Dynamic behavior of Skyrmions under the influence of periodic pinning in chiral magnetic infinite thin films Type Doctoral thesis
Year 2023 Publication Abbreviated Journal
Volume Issue Pages 212 p.
Keywords Doctoral thesis; Condensed Matter Theory (CMT)
Abstract The miniaturization of transistors for application in new processors and logic devices poses a significant challenge in the field of materials. Spintronics, which relies on controlled movement of magnetic nanostructures, offers a promising solution. Among the candidates, magnetic skyrmions are considered one of the most promising. These chiral spin structures, characterized by topological protection and enhanced stability compared to vortices or magnetic bubbles, have been extensively studied. To advance in the control of skyrmion motion, essential for practical applications, we investigated their dynamic behavior in a two-dimensional chiral magnet at zero temperature. Our study focused on the influence of periodic arrays of pinning centers. The simulations considered skyrmions as point-like particles considering the following interactions: skyrmion-skyrmion interactions, interactions with pinning center arrays, a current of polarized spins, and the Magnus force. We conducted calculations for scenarios involving a single skyrmion as well as different skyrmion density values in the material. The aim was to explore possibilities for controlled skyrmion motion, investigate different dynamic regimes, and examine collective effects. The results demonstrate that by adjusting the size, strength, and density of the pinning centers, we can effectively control the motion of individual skyrmions and manage the flow of multiple skyrmions. Furthermore, we discovered that periodic arrays of pinning centers can facilitate topological selection when different species of skyrmions with distinct Magnus components are present. Employing alternating currents, we observed the significant role of the ratchet effect in the skyrmion dynamics. By fine-tuning the amplitudes of the alternating currents, we achieved direct and controlled motion of skyrmions in specific directions. These findings hold potential for advancing our understanding of skyrmion dynamics and can inspire future technological applications involving these quasi-particles. Overall, we anticipate that our results will be valuable to the scientific community, contributing to a deeper comprehension of skyrmion dynamics and paving the way for future technological applications.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:198101 Serial 8852
Permanent link to this record
 

 
Author Hassani, H.
Title First-principles study of polarons in WO₃ Type Doctoral thesis
Year 2023 Publication Abbreviated Journal
Volume Issue Pages 181 p.
Keywords Doctoral thesis; Condensed Matter Theory (CMT)
Abstract Polarons are quasiparticles emerging in materials from the interaction of extra charge carriers with the surrounding atomic lattice. They appear in a wide va- riety of compounds and can have a profound impact on their properties, making the concept of a polaron a central and ubiquitous topic in material science. Al- though the concept is known for about 75 years, the origin of polarons is not yet fully elucidated. This thesis focuses on WO 3 as a well-known prototypical system for studying polarons, which inherent polaronic nature is linked to its remark- able electrical and chromic properties. The primary objective of this research is to provide a comprehensive atomistic description and understanding of polaron formation in WO 3 using first-principles density functional theory (DFT) calcula- tions. Additionally, the investigation explores the interactions between polarons and the possibility of bipolaron formation. Following a systematic strategy, we first extensively analyze the dielectric and lattice dynamical properties of WO 3 in both the room-temperature P 2 1 /n and ground-state P 2 1 /c phases. Our specific focus is on characterizing the zone-center phonons, which serve as the founda- tion for identifying the phonon modes involved in the polaron formation and charge localization process. Subsequently, we examine the impact of structural distortions on the electronic structure of WO 3 to elucidate the interplay between structural distortions and electronic properties, thereby laying the groundwork for understanding electron-phonon couplings. By incorporating these critical fac- tors, we address our primary research goals. The most common explanation for the polaron formation is associated with the electrostatic screening of the extra charge by the polarizable lattice. Here, we show that, even in ionic crystals, this is not necessarily the case. We demonstrate that polarons in this compound arise primarily from non-polar atomic distortions. We then unveil that this unexpected behavior originates from the undoing of distortive atomic motions, which lowers the bandgap. As such, we coin the name of anti-distortive polaron and validate its appearance through a simple quantum-dot model, in which charge localization is the result of balancing structural, electronic, and confinement energy costs. Then, we also study the polaron-polaron interaction and present the formation of the antiferromagnetic W 4+ bipolaronic state with relatively large formation energy. Our analysis of the W 4+ bipolaronic distortions on the global structure reveals the same behavior as in experiments where the highly distorted monoclinic phase transforms into a tetragonal phase as a function of doping. Additionally, leveraging our previous findings on asymmetric polaronic distortion and examin- ing different merging orientations, we stabilize the antiferromagnetic W 5+ -W 5+ bipolaronic state with an energy lower than the W 4+ state. This thesis clari- fies the formation of unusual medium-size 2D polarons and bipolarons in WO3,which might be relevant to the whole family of ABO 3 perovskites, to which WO 3 is closely related. The simplicity of the concept provides also obvious guidelines for tracking similar behavior in other families of compounds.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:198169 Serial 8868
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Author Blundo, E.; Faria, P.E., Jr.; Surrente, A.; Pettinari, G.; Prosnikov, M.A.; Olkowska-Pucko, K.; Zollner, K.; Wozniak, T.; Chaves, A.; Kazimierczuk, T.; Felici, M.; Babinski, A.; Molas, M.R.; Christianen, P.C.M.; Fabian, J.; Polimeni, A.
Title Strain-Induced Exciton Hybridization in WS2 Monolayers Unveiled by Zeeman-Splitting Measurements Type A1 Journal article
Year 2022 Publication Physical review letters Abbreviated Journal
Volume 129 Issue 6 Pages 067402
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Mechanical deformations and ensuing strain are routinely exploited to tune the band gap energy and to enhance the functionalities of two-dimensional crystals. In this Letter, we show that strain leads also to a strong modification of the exciton magnetic moment in WS2 monolayers. Zeeman-splitting measurements under magnetic fields up to 28.5 T were performed on single, one-layer-thick WS2 microbubbles. The strain of the bubbles causes a hybridization of k-space direct and indirect excitons resulting in a sizable decrease in the modulus of they factor of the ground-state exciton. These findings indicate that strain may have major effects on the way the valley number of excitons can be used to process binary information in two-dimensional crystals.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000842367600007 Publication Date 2022-08-04
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 (down) Times cited Open Access OpenAccess
Notes Approved no
Call Number UA @ admin @ c:irua:198538 Serial 8936
Permanent link to this record
 

 
Author Hasnat Rubel, A.
Title Theoretical characterization and optimization of nano-engineered superconducting scanning probe tip Type Doctoral thesis
Year 2023 Publication Abbreviated Journal
Volume Issue Pages viii, 145 p.
Keywords Doctoral thesis; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract Using state-of-the-art simulation methods, we optimized the performance of nanoscale superconducting scanning probe tips for advanced spatial imaging of magnetic fields. The systematic studies of the tips’ static properties as a function of the tilted magnetic field, geometric parameters, and material parameters were carried out. The sensitivity of different superconducting quantum interference devices (SQUIDs) to the magnetic field emanating from the magnetic nanoparticle, where the location of a magnetic nanoparticle is considered below the primary loop's center, was examined as a function of the primary and secondary loop dimensions. The main objective of the research was to characterize and optimize the performance of a nano-sized SQUID-on-tip (SOT) device. Optimal SOT sensitivity was sought, for different loop sizes, arm linewidth, and lead dimensions. Moreover, we revealed that a constriction in the loop arms of the SOT can substantially improve the sensitivity of the device. Finally, the properties of the theta-SOT device were examined in the presence of in-plane and out-of-plane magnetic field components, enabling nanoscale imaging of 3D distributions of the magnetic field. Altogether, the obtained results deliver an engineering solution for the optimum performance of the SOT device in desired conditions.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:199494 Serial 8942
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Author Reyntjens, P.; Van de Put, M.; Vandenberghe, W.G.; Sorée, B.
Title Ultrascaled graphene-capped interconnects : a quantum mechanical study Type P1 Proceeding
Year 2023 Publication Proceedings of the IEEE ... International Interconnect Technology Conference T2 – IEEE International Interconnect Technology Conference (IITC) / IEEE, Materials for Advanced Metallization Conference (MAM), MAY 22-25, 2023, Dresden, Germany Abbreviated Journal
Volume Issue Pages 1-3
Keywords P1 Proceeding; Condensed Matter Theory (CMT)
Abstract In this theoretical study, we assess the impact of a graphene capping layer on the resistivity of defective, extremely scaled interconnects. We investigate the effect of graphene capping on the electronic transport in ultrascaled interconnects, in the presence of grain boundary defects in the metal layer. We compare the results obtained using our quantum mechanical model to a simple parallel-conductor model and find that the parallel-conductor model does not capture the effect of the graphene cap correctly. At 0.5 nm metal thickness, the parallel-conductor model underestimates the conductivity by 3.0% to 4.0% for single-sided and double sided graphene capping, respectively.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001027381700006 Publication Date 2023-06-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 979-83-503-1097-9 ISBN Additional Links UA library record; WoS full record
Impact Factor (down) Times cited Open Access Not_Open_Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:198343 Serial 8949
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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 001170769300001 Publication Date 2024-02-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) Times cited Open Access Not_Open_Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:202983 Serial 9012
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Author McLachlan, G.; Majdak, P.; Reijniers, J.; Mihocic, M.; Peremans, H.
Title Dynamic spectral cues do not affect human sound localization during small head movements Type A1 Journal article
Year 2023 Publication Frontiers in neuroscience Abbreviated Journal
Volume 17 Issue Pages 1027827-10
Keywords A1 Journal article; Psychology; Condensed Matter Theory (CMT); Engineering Management (ENM)
Abstract Natural listening involves a constant deployment of small head movement. Spatial listening is facilitated by head movements, especially when resolving front-back confusions, an otherwise common issue during sound localization under head-still conditions. The present study investigated which acoustic cues are utilized by human listeners to localize sounds using small head movements (below ±10° around the center). Seven normal-hearing subjects participated in a sound localization experiment in a virtual reality environment. Four acoustic cue stimulus conditions were presented (full spectrum, flattened spectrum, frozen spectrum, free-field) under three movement conditions (no movement, head rotations over the yaw axis and over the pitch axis). Localization performance was assessed using three metrics: lateral and polar precision error and front-back confusion rate. Analysis through mixed-effects models showed that even small yaw rotations provide a remarkable decrease in front-back confusion rate, whereas pitch rotations did not show much of an effect. Furthermore, MSS cues improved localization performance even in the presence of dITD cues. However, performance was similar between stimuli with and without dMSS cues. This indicates that human listeners utilize the MSS cues before the head moves, but do not rely on dMSS cues to localize sounds when utilizing small head movements.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000938567400001 Publication Date 2023-02-03
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 1662-4548; 1662-453x ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:194507 Serial 9025
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Author Rakesh Roshan, S.C.; Yedukondalu, N.; Pandey, T.; Kunduru, L.; Muthaiah, R.; Rajaboina, R.K.; Ehm, L.; Parise, J.B.
Title Effect of atomic mass contrast on lattice thermal conductivity : a case study for alkali halides and alkaline-earth chalcogenides Type A1 Journal article
Year 2023 Publication ACS applied electronic materials Abbreviated Journal
Volume 5 Issue 11 Pages 5852-5863
Keywords A1 Journal article; Condensed Matter Theory (CMT)
Abstract Lattice thermal conductivity (kappa(L)) is of great scientific interest for the development of efficient energy conversion technologies. Therefore, microscopic understanding of phonon transport is critically important for designing functional materials. In our previous study (Roshan et al., ACS Applied Energy Mater. 2021, 5, 882-896), anomalous kappa(L) trends were predicted for rocksalt alkaline-earth chalcogenides (AECs). In the present work, we extended it to alkali halides (AHs) and conducted a thorough investigation to explore the role of atomic mass contrast on lattice dynamics and phonon transport properties of 36 binary compounds (20 AHs + 16 AECs). The calculated spectral and cumulative kappa(L) reveal that low-lying optical phonon modes significantly boost kappa(L) alongside acoustic phonons in materials where the atomic mass ratio approaches unity and cophonocity nears zero. Phonon scattering rates are relatively low for materials with a mass ratio close to one, and the corresponding phonon lifetimes are higher, which enhances kappa(L). Phonon lifetimes play a critical role, outweighing phonon group velocities, in determining the anomalous trends in kappa(L) for both AHs and AECs. To further explore the role of atomic mass contrast in kappa(L), the effect of tensile lattice strain on phonon transport has also been investigated. Under tensile strain, both group velocities and phonon lifetimes decrease in the low frequency range, leading to a decrease in kappa(L). This work provides insights on how atomic mass contrast can tune the contribution of optical phonons to kappa(L) and its implications on scattering rates by either enhancing or suppressing kappa(L). These insights would aid in the selection of elements for designing new functional materials with and without atomic mass contrast to achieve relatively high and low kappa(L) values, respectively.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001096792500001 Publication Date 2023-10-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2637-6113 ISBN Additional Links UA library record; WoS full record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:201198 Serial 9026
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Author Reijniers, J.; Partoens, B.; Peremans, H.
Title Noise-resistant correlation-based alignment of head-related transfer functions for high-fidelity spherical harmonics representation Type P3 Proceeding
Year 2023 Publication Abbreviated Journal
Volume Issue Pages
Keywords P3 Proceeding; Engineering sciences. Technology; Engineering Management (ENM); Condensed Matter Theory (CMT)
Abstract It is standard practice in virtual reality applications to synthesize binaural audio based on a discrete set of directionally-dependent head-related impulse responses (HRIRs). This set of HRIRs is often time-aligned in a pre-processing step, to allow for high-fidelity interpolation between HRIRs corresponding with neighbouring directions. The fidelity of this operation depends on the similarity of neighbouring aligned HRIRs. The pairwise quality of similarity makes it a difficult criterion to optimize globally and consequently one often resorts to alignment methods based on a specific feature that can be extracted for each HRIR separately, e.g., the first-onset of the peak or the group delay. However, such proxies for similarity are very sensitive to noise and therefore require a high signal-to-noise ratio, which makes them less suitable for processing HRIRs acquired outside an anechoic room. In this paper, we advance a novel alignment method, which maximizes the similarity – defined as the correlation between the full-length HRIRs – between neighbouring aligned HRIRs for all directions at once. We show that this correlation-based alignment procedure outperforms the first-onset alignment with regards to the fidelity of the spherical harmonics representation of both the spectral and interaural time difference (ITD) information, when tested on the KEMAR HRIR and six human HRIRs. Finally, we show that the correlation-based alignment is more robust to noise.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:199714 Serial 9062
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Author Deylgat, E.; Chen, E.; Sorée, B.; Vandenberghe, W.G.
Title Quantum transport study of contact resistance of edge- and top-contacted two-dimensional materials Type P1 Proceeding
Year 2023 Publication International Conference on Simulation of Semiconductor Processes and Devices : [proceedings] T2 – International Conference on Simulation of Semiconductor Processes and, Devices (SISPAD), SEP 27-29, 2023, Kobe, Japan Abbreviated Journal
Volume Issue Pages 45-48
Keywords P1 Proceeding; Condensed Matter Theory (CMT)
Abstract We calculate the contact resistance for an edge- and top-contacted 2D semiconductor. The contact region consists of a metal contacting a monolayer of MoS2 which is otherwise surrounded by SiO2. We use the quantum transmitting boundary method to compute the contact resistance as a function of the 2D semiconductor doping concentration. An effective mass Hamiltonian is used to describe the properties of the various materials. The electrostatic potentials are obtained by solving the Poisson equation numerically. We incorporate the effects of the image-force barrier lowering on the Schottky barrier and examine the impact on the contact resistance. At low doping concentrations, the contact resistance of the top contact is lower compared to edge contact, while at high doping concentrations, the edge contact exhibits lower resistance.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001117703800012 Publication Date 2023-11-20
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 978-4-86348-803-8 ISBN Additional Links UA library record; WoS full record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:202839 Serial 9079
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Author Jorissen, B.; Fernandes, L.
Title Simple systems, complicated physics : an interview with Nir Navon Type Editorial
Year 2023 Publication Belgian journal of physics Abbreviated Journal
Volume 1 Issue 6 Pages 4-5
Keywords Editorial; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Abstract The EPS Antwerp Young Minds (AYM) invited Prof. Nir Navon (Yale University) to hold a colloquium for the physics department. For an audience of students and researchers, Prof. Navon presented recent advances in ultracold quantum matter and research from his own lab. His experimental work paves the way to make toy models used by theorists a reality. We sat down afterwards to discuss ultracold physics, box traps and setting up a lab from scratch.
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Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:202673 Serial 9090
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Author Vermeulen, B.B.; Raymenants, E.; Pham, V.T.; Pizzini, S.; Sorée, B.; Wostyn, K.; Couet, S.; Nguyen, V.D.; Temst, K.
Title Towards fully electrically controlled domain-wall logic Type A1 Journal article
Year 2024 Publication AIP advances Abbreviated Journal
Volume 14 Issue 2 Pages 025030-25035
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract Utilizing magnetic tunnel junctions (MTJs) for write/read and fast spin-orbit-torque (SOT)-driven domain-wall (DW) motion for propagation, enables non-volatile logic and majority operations, representing a breakthrough in the implementation of nanoscale DW logic devices. Recently, current-driven DW logic gates have been demonstrated via magnetic imaging, where the Dzyaloshinskii-Moriya interaction (DMI) induces chiral coupling between perpendicular magnetic anisotropy (PMA) regions via an in-plane (IP) oriented region. However, full electrical operation of nanoscale DW logic requires electrical write/read operations and a method to pattern PMA and IP regions compatible with the fabrication of PMA MTJs. Here, we study the use of a Hybrid Free Layer (HFL) concept to combine an MTJ stack with DW motion materials, and He+ ion irradiation to convert the stack from PMA to IP. First, we investigate the free layer thickness dependence of 100-nm diameter HFL-MTJ devices and find an optimal CoFeB thickness, from 7 to 10 angstrom, providing high tunneling magnetoresistance (TMR) readout and efficient spin-transfer torque (STT) writing. We then show that high DMI materials, like Pt/Co, can be integrated into an MTJ stack via interlayer exchange coupling with the CoFeB free layer. In this design, DMI values suitable for SOT-driven DW motion are measured by asymmetric bubble expansion. Finally, we demonstrate that He+ irradiation reliably converts the coupled free layers from PMA to IP. These findings offer a path toward the integration of fully electrically controlled DW logic circuits.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 001163573400005 Publication Date 2024-02-16
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2158-3226 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor (down) Times cited Open Access Not_Open_Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:203823 Serial 9109
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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 (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:205972 Serial 9151
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Author Vermeulen, B.B.; Sorée, B.; Couet, S.; Temst, K.; Van Nguyen, D.
Title Progress in spin logic devices based on domain-wall motion Type A1 Journal article
Year 2024 Publication Micromachines Abbreviated Journal
Volume 15 Issue 6 Pages 696-20
Keywords A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT)
Abstract Spintronics, utilizing both the charge and spin of electrons, benefits from the nonvolatility, low switching energy, and collective behavior of magnetization. These properties allow the development of magnetoresistive random access memories, with magnetic tunnel junctions (MTJs) playing a central role. Various spin logic concepts are also extensively explored. Among these, spin logic devices based on the motion of magnetic domain walls (DWs) enable the implementation of compact and energy-efficient logic circuits. In these devices, DW motion within a magnetic track enables spin information processing, while MTJs at the input and output serve as electrical writing and reading elements. DW logic holds promise for simplifying logic circuit complexity by performing multiple functions within a single device. Nevertheless, the demonstration of DW logic circuits with electrical writing and reading at the nanoscale is still needed to unveil their practical application potential. In this review, we discuss material advancements for high-speed DW motion, progress in DW logic devices, groundbreaking demonstrations of current-driven DW logic, and its potential for practical applications. Additionally, we discuss alternative approaches for current-free information propagation, along with challenges and prospects for the development of DW logic.
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:001256 Publication Date 2024-05-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 2072-666x ISBN Additional Links UA library record; WoS full record; WoS full record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:207054 Serial 9312
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Author Pascucci, F.
Title Superfluidity in exciton bilayer systems : Josephson effect and collective modes as definitive identification-markers Type Doctoral thesis
Year 2024 Publication Abbreviated Journal
Volume Issue Pages xiii, 126 p.
Keywords Doctoral thesis; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT)
Abstract This thesis explores superfluidity in exciton bilayer systems, semiconductor structures with two thin conducting layers, one doped with electrons and the other with holes, separated by a few nanometers. Theoretical predictions suggest these systems can exhibit superfluid, supersolid, exciton normal solid, and Wigner crystal phases. Identifying clear markers of superfluidity is crucial due to experimental challenges in confirming excitonic superfluidity. This thesis focuses on two phenomena: the Josephson effect and density collective modes. For the Josephson effect, we propose an exciton bilayer Josephson junction in double monolayer Transition Metal Dichalcogenides. We suggest using the Shapiro method to measure the exciton Josephson current and propose fabricating the device with a tunable potential-barrier height. In low potential-barrier regions, the exciton superfluid flows over the barrier, while in high potential-barrier regions, flow is driven by quantum tunnelling. This helps delineate the boundary between Bose-Einstein Condensate (BEC) and BCS-BEC crossover regimes. For density collective modes, we examine low-temperature behaviour to identify the normal-superfluid transition as a function of density. In the normal state at high density, the system exhibits low-energy optic and acoustic modes. As density decreases, entering the superfluid phase, the response changes, with the superfluid gap blocking these modes. We expect pair-breaking collective modes to appear at the onset of exciton superfluidity due to the Coulomb interaction. Our theoretical model developed using a path-integral approach and the Hartree-Fock approximation, includes screening and intralayer correlations. We calculate gap and number equations governing superfluid phase behaviour, showing that intralayer correlations enhance screening, especially in the BCS-BEC crossover regime. This leads to a reduced superfluid gap, a shift in the BEC to BCS-BEC crossover boundary to lower densities, and the disappearance of a predicted minimum in electron-hole pair size. This study advances the understanding of superfluidity in exciton bilayer systems, providing theoretical predictions and experimental proposals. By identifying clear markers of superfluidity, this work contributes to the broader effort of realizing and characterizing excitonic condensed phases in realistic systems.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos Publication Date 2024-09-13
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN ISBN Additional Links UA library record
Impact Factor (down) Times cited Open Access
Notes Approved Most recent IF: NA
Call Number UA @ admin @ c:irua:207852 Serial 9318
Permanent link to this record