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Author |
Curran, P.J.; Desoky, W.M.; Milošević, M.V.; Chaves, A.; Laloe, J.-B.; Moodera, J.S.; Bending, S.J. |
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Title |
Spontaneous symmetry breaking in vortex systems with two repulsive lengthscales |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Scientific reports |
Abbreviated Journal |
Sci Rep-Uk |
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Volume  |
5 |
Issue |
5 |
Pages |
15569 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
Scanning Hall probe microscopy (SHPM) has been used to study vortex structures in thin epitaxial films of the superconductor MgB2. Unusual vortex patterns observed in MgB2 single crystals have previously been attributed to a competition between short-range repulsive and long-range attractive vortex-vortex interactions in this two band superconductor; the type 1.5 superconductivity scenario. Our films have much higher levels of disorder than bulk single crystals and therefore both superconducting condensates are expected to be pushed deep into the type 2 regime with purely repulsive vortex interactions. We observe broken symmetry vortex patterns at low fields in all samples after field-cooling from above T-c. These are consistent with those seen in systems with competing repulsions on disparate length scales, and remarkably similar structures are reproduced in dirty two band Ginzburg-Landau calculations, where the simulation parameters have been defined by experimental observations. This suggests that in our dirty MgB2 films, the symmetry of the vortex structures is broken by the presence of vortex repulsions with two different lengthscales, originating from the two distinct superconducting condensates. This represents an entirely new mechanism for spontaneous symmetry breaking in systems of superconducting vortices, with important implications for pinning phenomena and high current density applications. |
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Publisher |
Nature Publishing Group |
Place of Publication |
London |
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Wos |
000363306000002 |
Publication Date |
2015-10-23 |
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ISSN |
2045-2322 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
4.259 |
Times cited |
12 |
Open Access |
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Notes |
; P.J.C. and S.J.B. acknowledge support from EPSRC in the UK under grant number EP/J010626/1 and the NanoSC COST Action MP-1201. M.V.M. thanks the Research Foundation-Flanders (FWO) and CAPES Brazil. A.C. acknowledges the financial support of CNPq, under the PRONEX/FUNCAP and PQ programs. J.-B.L. and J.S.M. acknowledge ONR Grant N00014-06-01-0235. ; |
Approved |
Most recent IF: 4.259; 2015 IF: 5.578 |
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Call Number |
UA @ lucian @ c:irua:129450 |
Serial |
4248 |
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Author |
Chaves, A.; Azadani, J.G.; Alsalman, H.; da Costa, D.R.; Frisenda, R.; Chaves, A.J.; Song, S.H.; Kim, Y.D.; He, D.; Zhou, J.; Castellanos-Gomez, A.; Peeters, F.M.; Liu, Z.; Hinkle, C.L.; Oh, S.-H.; Ye, P.D.; Koester, S.J.; Lee, Y.H.; Avouris, P.; Wang, X.; Low, T. |
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Title |
Bandgap engineering of two-dimensional semiconductor materials |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
npj 2D Materials and Applications |
Abbreviated Journal |
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Volume |
4 |
Issue |
1 |
Pages |
29-21 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
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Abstract |
Semiconductors are the basis of many vital technologies such as electronics, computing, communications, optoelectronics, and sensing. Modern semiconductor technology can trace its origins to the invention of the point contact transistor in 1947. This demonstration paved the way for the development of discrete and integrated semiconductor devices and circuits that has helped to build a modern society where semiconductors are ubiquitous components of everyday life. A key property that determines the semiconductor electrical and optical properties is the bandgap. Beyond graphene, recently discovered two-dimensional (2D) materials possess semiconducting bandgaps ranging from the terahertz and mid-infrared in bilayer graphene and black phosphorus, visible in transition metal dichalcogenides, to the ultraviolet in hexagonal boron nitride. In particular, these 2D materials were demonstrated to exhibit highly tunable bandgaps, achieved via the control of layers number, heterostructuring, strain engineering, chemical doping, alloying, intercalation, substrate engineering, as well as an external electric field. We provide a review of the basic physical principles of these various techniques on the engineering of quasi-particle and optical bandgaps, their bandgap tunability, potentials and limitations in practical realization in future 2D device technologies. |
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Wos |
000565588500001 |
Publication Date |
2020-08-24 |
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ISSN |
2397-7132 |
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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 |
329 |
Open Access |
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Notes |
; Discussions and interactions with D.R. Reichman, F. Tavazza, N.M.R. Peres, and K. Choudhary are gratefully acknowledged. A.C. acknowledges financial support by CNPq, through the PRONEX/FUNCAP and PQ programs. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 755655, ERCStG 2017 project 2D-TOPSENSE). Computational support from the Minnesota Supercomputing Institute (MSI) and EU Graphene Flagship funding (Grant Graphene Core 2, 785219) is acknowledged. R.F. acknowledges support from the Netherlands Organization for Scientific Research (NWO) through the research program Rubicon with project number 680-50-1515. D.H., J.Z., and X.W. acknowledge support by National Natural Science Foundation of China 61734003, 61521001, 61704073, 51861145202, and 61851401, and National Key Basic Research Program of China 2015CB921600 and 2018YFB2200500. J.Z. and Z.L. acknowledge support by RG7/18, MOE2017-T2-2-136, MOE2018-T3-1-002, and A*Star QTE program. S.H.S. and Y.H.L. acknowledge the support from IBS-R011-D1. Y.D.K. is supported by Samsung Research and Incubation Funding Center of Samsung Electronics under Project Number SRFC-TB1803-04. S.J.K acknowledges financial support by the National Science Foundation (NSF), under award DMR-1921629. T.L. and J.G.A. acknowledge funding support from NSF/DMREF under Grant Agreement No. 1921629. S.-H.O. acknowledges support from the U.S. National Science Foundation (NSF ECCS 1809723) and Samsung Global Research Outreach (GRO) project. ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:172069 |
Serial |
6459 |
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Author |
Lavor, I.R.; Chaves, A.; Peeters, F.M.; Van Duppen, B. |
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Title |
Tunable coupling of terahertz Dirac plasmons and phonons in transition metal dichalcogenide-based van der Waals heterostructures |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
2d Materials |
Abbreviated Journal |
2D Mater |
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Issue |
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Pages |
015018 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Dirac plasmons in graphene hybridize with phonons of transition metal dichalcogenides (TMDs) when the materials are combined in so-called van der Waals heterostructures (vdWh), thus forming surface plasmon-phonon polaritons (SPPPs). The extend to which these modes are coupled depends on the TMD composition and structure, but also on the plasmons' properties. By performing realistic simulations that account for the contribution of each layer of the vdWh separately, we calculate how the strength of plasmon-phonon coupling depends on the number and composition of TMD layers, on the graphene Fermi energy and the specific phonon mode. From this, we present a semiclassical theory that is capable of capturing all relevant characteristics of the SPPPs. We find that it is possible to realize both strong and ultra-strong coupling regimes by tuning graphene's Fermi energy and changing TMD layer number. |
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Wos |
000722020100001 |
Publication Date |
2021-11-08 |
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ISSN |
2053-1583 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
6.937 |
Times cited |
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Open Access |
OpenAccess |
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Notes |
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Approved |
Most recent IF: 6.937 |
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Call Number |
UA @ admin @ c:irua:183053 |
Serial |
7036 |
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Author |
Conti, S.; Chaves, A.; Pandey, T.; Covaci, L.; Peeters, F.M.; Neilson, D.; Milošević, M.V. |
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Title |
Flattening conduction and valence bands for interlayer excitons in a moire MoS₂/WSe₂ heterobilayer |
Type |
A1 Journal article |
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Year |
2023 |
Publication |
Nanoscale |
Abbreviated Journal |
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Volume |
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Issue |
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Pages |
1-11 |
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Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
We explore the flatness of conduction and valence bands of interlayer excitons in MoS2/WSe2 van der Waals heterobilayers, tuned by interlayer twist angle, pressure, and external electric field. We employ an efficient continuum model where the moire pattern from lattice mismatch and/or twisting is represented by an equivalent mesoscopic periodic potential. We demonstrate that the mismatch moire potential is too weak to produce significant flattening. Moreover, we draw attention to the fact that the quasi-particle effective masses around the Gamma-point and the band flattening are reduced with twisting. As an alternative approach, we show (i) that reducing the interlayer distance by uniform vertical pressure can significantly increase the effective mass of the moire hole, and (ii) that the moire depth and its band flattening effects are strongly enhanced by accessible electric gating fields perpendicular to the heterobilayer, with resulting electron and hole effective masses increased by more than an order of magnitude – leading to record-flat bands. These findings impose boundaries on the commonly generalized benefits of moire twistronics, while also revealing alternative feasible routes to achieve truly flat electron and hole bands to carry us to strongly correlated excitonic phenomena on demand. |
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Wos |
001047512300001 |
Publication Date |
2023-07-25 |
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Abbreviated Series Title |
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ISSN |
2040-3364; 2040-3372 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
6.7 |
Times cited |
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Open Access |
Not_Open_Access: Available from 25.01.2024 |
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Notes |
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Approved |
Most recent IF: 6.7; 2023 IF: 7.367 |
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Call Number |
UA @ admin @ c:irua:198290 |
Serial |
8819 |
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