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Author |
Li, H.; Pandey, T.; Jiang, Y.; Gu, X.; Lindsay, L.; Koh, Y.K. |
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Title |
Origins of heat transport anisotropy in MoTe₂ and other bulk van der Waals materials |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Materials Today Physics |
Abbreviated Journal |
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Volume |
37 |
Issue |
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Pages |
101196-101198 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Knowledge of how heat flows anisotropically in van der Waals (vdW) materials is crucial for thermal management of emerging 2D materials devices and design of novel anisotropic thermoelectric materials. Despite the importance, anisotropic heat transport in vdW materials is yet to be systematically studied and is often presumably attributed to anisotropic speeds of sound in vdW materials due to soft interlayer bonding relative to covalent in-plane networks of atoms. In this work, we investigate the origins of the anisotropic heat transport in vdW materials, through time-domain thermoreflectance (TDTR) measurements and first-principles calculations of anisotropic thermal conductivity of three different phases of MoTe2. MoTe2 is ideal for the study due to its weak anisotropy in the speeds of sound. We find that even when the speeds of sound are roughly isotropic, the measured thermal conductivity of MoTe2 along the c-axis is 5-8 times lower than that along the in-plane axes. We derive meaningful characteristic heat capacity, phonon group velocity, and relaxation times from our first principles calculations for selected vdW materials (MoTe2, BP, h-BN, and MoS2), to assess the contributions of these factors to the anisotropic heat transport. Interestingly, we find that the main contributor to the heat transport anisotropy in vdW materials is anisotropy in heat capacity of the dominant heat-carrying phonon modes in different directions, which originates from anisotropic optical phonon dispersion and disparity in the frequency of heat-carrying phonons in different directions. The discrepancy in frequency of the heat-carrying phonons also leads to similar to 2 times larger average relaxation times in the cross-plane direction, and partially explains the apparent dependence of the anisotropic heat transport on the anisotropic speeds of sound. This work provides insight into understanding of the anisotropic heat transport in vdW materials. |
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Wos |
001093005700001 |
Publication Date |
2023-08-09 |
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ISSN |
2542-5293 |
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UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:201295 |
Serial |
9070 |
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Author |
Bekaert, J. |
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Title |
Phonon-mediated superconductivity in ternary silicides X₄ CoSi (X = Nb, Ta) |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Physical review B |
Abbreviated Journal |
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Volume |
108 |
Issue |
13 |
Pages |
134504-134507 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The superconducting properties of two recently synthesized ternary silicides with unit formula X<sub>4</sub>CoSi (X = Nb, Ta) are investigated through ab initio calculations combined with Eliashberg theory. Interestingly, their crystal structure comprises interlocking honeycomb networks of Nb/Ta atoms. Nb<sub>4</sub>CoSi is found to harbor better conditions for phonon-mediated superconductivity, as it possesses a higher density of states at the Fermi level, fostering stronger electron-phonon coupling. The superconducting critical temperatures (T<sub>c</sub>) follow the same trend, with Nb<sub>4</sub>CoSi having a twice higher value than Ta<sub>4</sub>CoSi. Furthermore, the calculated T<sub>c</sub> values (5.9 K vs 3.1 K) agree excellently with the experimentally obtained ones, establishing superconductivity in this new materials class as mediated by the electron-phonon coupling. Furthermore, my calculations show that the superconducting properties of these compounds do not simply correlate with the parameters of their honeycomb networks, contrary to proposals raised in the literature. Rather, their complete fermiology and phonon spectrum should be taken into account in order to explain their respective superconducting properties. |
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Wos |
001140080300003 |
Publication Date |
2023-10-17 |
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ISSN |
2469-9969; 2469-9950 |
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UA library record; WoS full record |
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Call Number |
UA @ admin @ c:irua:201445 |
Serial |
9071 |
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Author |
Wahab, O.J.; Daviddi, E.; Xin, B.; Sun, P.Z.; Griffin, E.; Colburn, A.W.; Barry, D.; Yagmurcukardes, M.; Peeters, F.M.; Geim, A.K.; Lozada-Hidalgo, M.; Unwin, P.R. |
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Title |
Proton transport through nanoscale corrugations in two-dimensional crystals |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Nature |
Abbreviated Journal |
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Volume |
620 |
Issue |
7975 |
Pages |
1-17 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
Defect-free graphene is impermeable to all atoms(1-5) and ions(6,7) under ambient conditions. Experiments that can resolve gas flows of a few atoms per hour through micrometre-sized membranes found that monocrystalline graphene is completely impermeable to helium, the smallest atom(2,5). Such membranes were also shown to be impermeable to all ions, including the smallest one, lithium(6,7). By contrast, graphene was reported to be highly permeable to protons, nuclei of hydrogen atoms(8,9). There is no consensus, however, either on the mechanism behind the unexpectedly high proton permeability(10-14) or even on whether it requires defects in graphene's crystal lattice(6,8,15-17). Here, using high-resolution scanning electrochemical cell microscopy, we show that, although proton permeation through mechanically exfoliated monolayers of graphene and hexagonal boron nitride cannot be attributed to any structural defects, nanoscale non-flatness of two-dimensional membranes greatly facilitates proton transport. The spatial distribution of proton currents visualized by scanning electrochemical cell microscopy reveals marked inhomogeneities that are strongly correlated with nanoscale wrinkles and other features where strain is accumulated. Our results highlight nanoscale morphology as an important parameter enabling proton transport through two-dimensional crystals, mostly considered and modelled as flat, and indicate that strain and curvature can be used as additional degrees of freedom to control the proton permeability of two-dimensional materials. A study using high-resolution scanning electrochemical cell microscopy attributes proton permeation through defect-free graphene and hexagonal boron nitride to transport across areas of the structure that are under strain. |
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Wos |
001153630400007 |
Publication Date |
2023-08-23 |
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Edition |
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ISSN |
0028-0836; 1476-4687 |
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UA library record; WoS full record; WoS citing articles |
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Call Number |
UA @ admin @ c:irua:203827 |
Serial |
9078 |
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Author |
Deylgat, E.; Chen, E.; Sorée, B.; Vandenberghe, W.G. |
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Title |
Quantum transport study of contact resistance of edge- and top-contacted two-dimensional materials |
Type |
P1 Proceeding |
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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 |
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Issue |
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Pages |
45-48 |
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Keywords |
P1 Proceeding; Condensed Matter Theory (CMT) |
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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. |
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Wos |
001117703800012 |
Publication Date |
2023-11-20 |
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Abbreviated Series Title |
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Edition |
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ISSN |
978-4-86348-803-8 |
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UA library record; WoS full record |
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no |
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Call Number |
UA @ admin @ c:irua:202839 |
Serial |
9079 |
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Author |
Zhang, C.; Ren, K.; Wang, S.; Luo, Y.; Tang, W.; Sun, M. |
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Title |
Recent progress on two-dimensional van der Waals heterostructures for photocatalytic water splitting : a selective review |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Journal of physics: D: applied physics |
Abbreviated Journal |
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Volume |
56 |
Issue |
48 |
Pages |
483001-483024 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Hydrogen production through photocatalytic water splitting is being developed swiftly to address the ongoing energy crisis. Over the past decade, with the rise of graphene and other two-dimensional (2D) materials, an increasing number of computational and experimental studies have focused on relevant van der Waals (vdW) semiconductor heterostructures for photocatalytic water splitting. In this review, the fundamental mechanism and distinctive performance of type-II and Z-scheme vdW heterostructure photocatalysts are presented. Accordingly, we have conducted a systematic review of recent studies focusing on candidates for photocatalysts, specifically vdW heterostructures involving 2D transition metal disulfides (TMDs), 2D Janus TMDs, and phosphorenes. The photocatalytic performance of these heterostructures and their suitability in theoretical scenarios are discussed based on their electronic and optoelectronic properties, particularly in terms of band structures, photoexcited carrier dynamics, and light absorption. In addition, various approaches for tuning the performance of these potential photocatalysts are illustrated. This strategic framework for constructing and modulating 2D heterostructure photocatalysts is expected to provide inspiration for addressing possible challenges in future studies. |
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Wos |
001076327300001 |
Publication Date |
2023-08-30 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-3727 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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no |
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Call Number |
UA @ admin @ c:irua:200353 |
Serial |
9081 |
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Author |
Santos-Castro, G.; Pandey, T.; Bruno, C.H.V.; Santos Caetano, E.W.; Milošević, M.V.; Chaves, A.; Freire, V.N. |
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Title |
Silicon and germanium adamantane and diamantane monolayers as two-dimensional anisotropic direct-gap semiconductors |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Physical review B |
Abbreviated Journal |
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Volume |
108 |
Issue |
3 |
Pages |
035302-35310 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Structural and electronic properties of silicon and germanium monolayers with two different diamondoid crystal structures are detailed ab initio. Our results show that, despite Si and Ge being well-known indirect gap semiconductors in their bulk form, their adamantane and diamantane monolayers can exhibit optically active direct gap in the visible frequency range, with highly anisotropic effective masses, depending on the monolayer crystal structure. Moreover, we reveal that gaps in these materials are highly tunable with applied strain. These stable monolayer forms of Si and Ge are therefore expected to help bridging the gap between the fast growing area of opto-electronics in two-dimensional materials and the established silicon-based technologies. |
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Wos |
001074455300012 |
Publication Date |
2023-07-05 |
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Abbreviated Series Title |
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Edition |
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ISSN |
2469-9969; 2469-9950 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Open Access |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:200348 |
Serial |
9089 |
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Author |
Jorissen, B.; Fernandes, L. |
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Title |
Simple systems, complicated physics : an interview with Nir Navon |
Type |
Editorial |
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Year |
2023 |
Publication |
Belgian journal of physics |
Abbreviated Journal |
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Volume |
1 |
Issue |
6 |
Pages |
4-5 |
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Keywords |
Editorial; Theory of quantum systems and complex systems; Condensed Matter Theory (CMT) |
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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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Additional Links |
UA library record |
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no |
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Call Number |
UA @ admin @ c:irua:202673 |
Serial |
9090 |
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Author |
Souza, J.C.B.; Vizarim, N.P.; Reichhardt, C.J.O.; Reichhardt, C.; Venegas, P.A. |
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Title |
Soliton motion induced along ferromagnetic skyrmion chains in chiral thin nanotracks |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Journal of magnetism and magnetic materials |
Abbreviated Journal |
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Volume |
587 |
Issue |
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Pages |
171280-171289 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Using atomistic magnetic simulations we investigate the soliton motion along a pinned skyrmion chain containing an interstitial skyrmion. We find that the soliton can exhibit stable motion along the chain without a skyrmion Hall effect for an extended range of drives. Under a constant drive the solitons have a constant velocity. We also measure the skyrmion velocity-current curves and identify the signatures of different phases including a pinned phase, stable soliton motion, and quasi-free motion at higher drives where all of the skyrmions depin from the pinning centers and move along the rigid wall. In the quasi-free motion regime, the velocity is oscillatory due to the motion of the skyrmions over the pinning sites. For increasing pinning strength, the onset of soliton motion shifts to higher values of current density. We also find that for stronger pinning, the characteristic velocity-current shape is affected by the annihilation of single or multiple skyrmions in the drive interval over which the soliton motion occurs. Our results indicate that stable skyrmion soliton motion is possible and that the solitons could be used as information carriers instead of the skyrmions themselves for technological applications. |
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Wos |
001086712600001 |
Publication Date |
2023-09-21 |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0304-8853 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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no |
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Call Number |
UA @ admin @ c:irua:201139 |
Serial |
9095 |
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Author |
Zamani, M.; Yapicioglu, H.; Kara, A.; Sevik, C. |
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Title |
Statistical analysis of porcelain tiles' technical properties : full factorial design investigation on oxide ratios and temperature |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Physica scripta |
Abbreviated Journal |
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Volume |
98 |
Issue |
12 |
Pages |
125953-18 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
This study focuses on optimizing the composition and firing temperature of porcelain tiles using statistical analysis techniques. A full factorial design, including model adequacy checking, analysis of variance, Pareto charts, interaction plots, regression model, and response optimizer is employed. The key factors were the Seger ratios of SiO2/Al2O3, Na2O/K2O, MgO/CaO, and firing temperature. The response variables investigated were bulk density, water absorption, linear shrinkage, coefficient of thermal expansion (at 500 degrees C), and strength. The statistical analysis revealed highly significant results, which were further validated, confirming their reliability for practical use in the production of porcelain tiles. The study demonstrated the effectiveness of utilizing Seger formulas and properties of typical raw materials to accurately predict the final properties of ceramic tiles. By employing SiO2/Al2O3 = 5.2, Na2O/K2O = 1.50, MgO/CaO = 3.0, and firing temperature of 1180 degrees C, optimized properties, such as maximum strength, maximum bulk density, and minimum water absorption, was achieved with a composite desirability of 0.9821. |
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Wos |
001105879800001 |
Publication Date |
2023-11-08 |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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ISSN |
0031-8949; 1402-4896 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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no |
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Call Number |
UA @ admin @ c:irua:202033 |
Serial |
9097 |
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Author |
Lauwens, J.; Kerkhofs, L.; Sala, A.; Sorée, B. |
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Title |
Superconductor-semiconductor hybrid capacitance with a nonlinear charge-voltage profile |
Type |
A1 Journal article |
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Year |
2024 |
Publication |
Journal of physics: D: applied physics |
Abbreviated Journal |
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Volume |
57 |
Issue |
2 |
Pages |
025301-25309 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Electronic devices that work in the quantum regime often employ hybrid nanostructures to bring about a nonlinear behaviour. The nonlinearity that these can provide has proven to be useful, in particular, for applications in quantum computation. Here we present a hybrid device that acts as a capacitor with a nonlinear charge-voltage relation. The device consists of a nanowire placed between the plates of a coplanar capacitor, with a co-parallel alignment. At low temperatures, due to the finite density of states on the nanowire, the charge distribution in the capacitor is uneven and energy-dependent, resulting in a charge-dependent effective capacitance. We study this system analytically and numerically, and show that the nonlinearity of the capacitance is significant enough to be utilized in circuit quantum electrodynamics. The resulting nonlinearity can be switched on, modulated, and switched off by an external potential, thus making this capacitive device highly versatile for uses in quantum computation. |
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Wos |
001082883200001 |
Publication Date |
2023-09-29 |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0022-3727 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Call Number |
UA @ admin @ c:irua:200300 |
Serial |
9099 |
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Author |
Tran, T.T.; Lee, Y.; Roy, S.; Tran, T.U.; Kim, Y.; Taniguchi, T.; Watanabe, K.; Milošević, M.V.; Lim, S.C.; Chaves, A.; Jang, J.I.; Kim, J. |
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Title |
Synergetic enhancement of quantum yield and exciton lifetime of monolayer WS₂ by proximal metal plate and negative electric bias |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
ACS nano |
Abbreviated Journal |
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Volume |
18 |
Issue |
1 |
Pages |
220-228 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
The efficiency of light emission is a critical performance factor for monolayer transition metal dichalcogenides (1L-TMDs) for photonic applications. While various methods have been studied to compensate for lattice defects to improve the quantum yield (QY) of 1L-TMDs, exciton-exciton annihilation (EEA) is still a major nonradiative decay channel for excitons at high exciton densities. Here, we demonstrate that the combined use of a proximal Au plate and a negative electric gate bias (NEGB) for 1L-WS2 provides a dramatic enhancement of the exciton lifetime at high exciton densities with the corresponding QY enhanced by 30 times and the EEA rate constant decreased by 80 times. The suppression of EEA by NEGB is attributed to the reduction of the defect-assisted EEA process, which we also explain with our theoretical model. Our results provide a synergetic solution to cope with EEA to realize high-intensity 2D light emitters using TMDs. |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
001139516800001 |
Publication Date |
2023-12-21 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
1936-0851 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:202811 |
Serial |
9101 |
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| Permanent link to this record |
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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. |
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Title |
Terahertz optoelectronic properties of synthetic single crystal diamond |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Diamond and related materials |
Abbreviated Journal |
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Volume |
139 |
Issue |
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Pages |
110266-110268 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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. |
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Corporate Author |
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Place of Publication |
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Wos |
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Publication Date |
2023-08-02 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0925-9635 |
ISBN |
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Additional Links |
UA library record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:200920 |
Serial |
9103 |
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Author |
Sargin, G.O.; Sarikurt, S.; Sevincli, H.; Sevik, C. |
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Title |
The peculiar potential of transition metal dichalcogenides for thermoelectric applications : a perspective on future computational research |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Journal of applied physics |
Abbreviated Journal |
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Volume |
133 |
Issue |
15 |
Pages |
150902-150937 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
The peculiar potential transition metal dichalcogenides in regard to sensor and device applications have been exhibited by both experimental and theoretical studies. The use of these materials, thermodynamically stable even at elevated temperatures, particularly in nano- and optoelectronic technology, is about to come true. On the other hand, the distinct electronic and thermal transport properties possessing unique coherency, which may result in higher thermoelectric efficiency, have also been reported. However, exploiting this potential in terms of power generation and cooling applications requires a deeper understanding of these materials in this regard. This perspective study, concentrated with this intention, summarizes thermoelectric research based on transition metal dichalcogenides from a broad perspective and also provides a general evaluation of future theoretical investigations inevitable to shed more light on the physics of electronic and thermal transport in these materials and to lead future experimental research. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
001079329000001 |
Publication Date |
2023-04-27 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0021-8979; 1089-7550 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:200351 |
Serial |
9105 |
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| Permanent link to this record |
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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. |
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Title |
Towards fully electrically controlled domain-wall logic |
Type |
A1 Journal article |
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Year |
2024 |
Publication |
AIP advances |
Abbreviated Journal |
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Volume |
14 |
Issue |
2 |
Pages |
025030-25035 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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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. |
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Corporate Author |
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Place of Publication |
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Language |
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Wos |
001163573400005 |
Publication Date |
2024-02-16 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2158-3226 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:203823 |
Serial |
9109 |
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| Permanent link to this record |
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Author |
Lima, I.L.C.; Milošević, M.V.; Peeters, F.M.; Chaves, A. |
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Title |
Tuning of exciton type by environmental screening |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Physical review B |
Abbreviated Journal |
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Volume |
108 |
Issue |
11 |
Pages |
115303-115308 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We theoretically investigate the binding energy and electron-hole (e-h) overlap of excitonic states confined at the interface between two-dimensional materials with type-II band alignment, i.e., with lowest conduction and highest valence band edges placed in different materials, arranged in a side-by-side planar heterostructure. We propose a variational procedure within the effective mass approximation to calculate the exciton ground state and apply our model to a monolayer MoS2/WS2 heterostructure. The role of nonabrupt interfaces between the materials is accounted for in our model by assuming a WxMo1-xS2 alloy around the interfacial region. Our results demonstrate that (i) interface-bound excitons are energetically favorable only for small interface thickness and/or for systems under high dielectric screening by the materials surrounding the monolayer, and that (ii) the interface exciton binding energy and its e-h overlap are controllable by the interface width and dielectric environment. |
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Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
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Editor |
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Language |
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Wos |
001077758300002 |
Publication Date |
2023-09-08 |
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Series Editor |
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Series Title |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
2469-9969; 2469-9950 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
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Times cited |
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Open Access |
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Notes |
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Approved |
no |
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Call Number |
UA @ admin @ c:irua:200356 |
Serial |
9110 |
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| Permanent link to this record |
