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Yan M, Deng W, Huang X, Wu Y, Yang Y, Lu J, Li F, Liu Z. Pseudomagnetic Fields Enabled Manipulation of On-Chip Elastic Waves. PHYSICAL REVIEW LETTERS 2021; 127:136401. [PMID: 34623863 DOI: 10.1103/physrevlett.127.136401] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
The physical realization of pseudomagnetic fields (PMFs) is an engaging frontier of research. As in graphene, elastic PMF can be realized by the structural modulations of Dirac materials. We show that, in the presence of PMFs, the conical dispersions split into elastic Landau levels, and the elastic modes robustly propagate along the edges, similar to the quantum Hall edge transports. In particular, we reveal unique elastic snake states in an on-chip heterostructure with two opposite PMFs. The flexibility in the micromanufacture of silicon chips and the low loss of elastic waves provide an unprecedented opportunity to demonstrate various fascinating topological transports of the edge states under PMFs. These properties open new possibilities for designing functional elastic wave devices in miniature and compact scales.
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Affiliation(s)
- Mou Yan
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Weiyin Deng
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Xueqin Huang
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Ying Wu
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Yating Yang
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Jiuyang Lu
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Feng Li
- School of Physics and Optoelectronics, South China University of Technology, Guangzhou, Guangdong 510640, China
| | - Zhengyou Liu
- Key Laboratory of Artificial Micro- and Nanostructures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan 430072, China
- Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
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2
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Banerjee R, Nguyen VH, Granzier-Nakajima T, Pabbi L, Lherbier A, Binion AR, Charlier JC, Terrones M, Hudson EW. Strain Modulated Superlattices in Graphene. NANO LETTERS 2020; 20:3113-3121. [PMID: 32134680 DOI: 10.1021/acs.nanolett.9b05108] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Numerous theoretically proposed devices and novel phenomena have sought to take advantage of the intense pseudogauge fields that can arise in strained graphene. Many of these proposals, however, require fields to oscillate with a spatial frequency smaller than the magnetic length, while to date only the generation and effects of fields varying at a much larger length scale have been reported. Here, we describe the creation of short wavelength, periodic pseudogauge-fields using rippled graphene under extreme (>10%) strain and study of its effects on Dirac electrons. Combining scanning tunneling microscopy and atomistic calculations, we find that spatially oscillating strain generates a new quantization different from the familiar Landau quantization. Graphene ripples also cause large variations in carbon-carbon bond length, creating an effective electronic superlattice within a single graphene sheet. Our results thus also establish a novel approach of synthesizing effective 2D lateral heterostructures by periodically modulating lattice strain.
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Affiliation(s)
- Riju Banerjee
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Viet-Hung Nguyen
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Chemin des étoiles 8, B-1348 Louvain-la-Neuve, Belgium
| | - Tomotaroh Granzier-Nakajima
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Lavish Pabbi
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Aurelien Lherbier
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Chemin des étoiles 8, B-1348 Louvain-la-Neuve, Belgium
| | - Anna Ruth Binion
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Jean-Christophe Charlier
- Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain, Chemin des étoiles 8, B-1348 Louvain-la-Neuve, Belgium
| | - Mauricio Terrones
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Eric William Hudson
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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3
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Jin D, Xia Y, Christensen T, Freeman M, Wang S, Fong KY, Gardner GC, Fallahi S, Hu Q, Wang Y, Engel L, Xiao ZL, Manfra MJ, Fang NX, Zhang X. Topological kink plasmons on magnetic-domain boundaries. Nat Commun 2019; 10:4565. [PMID: 31594922 PMCID: PMC6783483 DOI: 10.1038/s41467-019-12092-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 07/31/2019] [Indexed: 11/09/2022] Open
Abstract
Two-dimensional topological materials bearing time reversal-breaking magnetic fields support protected one-way edge modes. Normally, these edge modes adhere to physical edges where material properties change abruptly. However, even in homogeneous materials, topology still permits a unique form of edge modes – kink modes – residing at the domain boundaries of magnetic fields within the materials. This scenario, despite being predicted in theory, has rarely been demonstrated experimentally. Here, we report our observation of topologically-protected high-frequency kink modes – kink magnetoplasmons (KMPs) – in a GaAs/AlGaAs two-dimensional electron gas (2DEG) system. These KMPs arise at a domain boundary projected from an externally-patterned magnetic field onto a uniform 2DEG. They propagate unidirectionally along the boundary, protected by a difference of gap Chern numbers (\documentclass[12pt]{minimal}
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\begin{document}$$\pm1$$\end{document}±1) in the two domains. They exhibit large tunability under an applied magnetic field or gate voltage, and clear signatures of nonreciprocity even under weak-coupling to evanescent photons. Topological kink modes are peculiar edge excitations that take place at domain boundaries of magnetic fields inside homogeneous materials. Here, the authors experimentally observe kink magnetoplasmons in a 2D electron gas using custom-shaped strong permanent magnets on top of a GaAs/AlGaAs heterojunction.
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Affiliation(s)
- Dafei Jin
- Nanoscale Science and Engineering Center, University of California, Berkeley, CA, 94706, USA.,Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Yang Xia
- Nanoscale Science and Engineering Center, University of California, Berkeley, CA, 94706, USA
| | - Thomas Christensen
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Matthew Freeman
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Siqi Wang
- Nanoscale Science and Engineering Center, University of California, Berkeley, CA, 94706, USA
| | - King Yan Fong
- Nanoscale Science and Engineering Center, University of California, Berkeley, CA, 94706, USA
| | - Geoffrey C Gardner
- Microsoft Quantum Purdue and Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Saeed Fallahi
- Department of Physics and Astronomy and Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Qing Hu
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Yuan Wang
- Nanoscale Science and Engineering Center, University of California, Berkeley, CA, 94706, USA
| | - Lloyd Engel
- National High Magnetic Field Laboratory, Tallahassee, FL, 32310, USA
| | - Zhi-Li Xiao
- Material Science Division, Argonne National Laboratory, Argonne, IL, 60439, USA
| | - Michael J Manfra
- Microsoft Quantum Purdue, Department of Physics and Astronomy, Birck Nanotechnology Center, Schools of Electrical and Computer Engineering and Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - Nicholas X Fang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Xiang Zhang
- Nanoscale Science and Engineering Center, University of California, Berkeley, CA, 94706, USA. .,Faculties of Sciences and Engineering University of Hong Kong, Hong Kong SAR, PR, China.
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4
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Man Z, Bai Z, Zhang S, Li J, Li X, Ge X, Zhang Y, Fu S. Focusing properties of arbitrary optical fields combining spiral phase and cylindrically symmetric state of polarization. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2018; 35:1014-1020. [PMID: 29877346 DOI: 10.1364/josaa.35.001014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 04/30/2018] [Indexed: 06/08/2023]
Abstract
The tight focusing properties of optical fields combining a spiral phase and cylindrically symmetric state of polarization are presented. First, we theoretically analyze the mathematical characterization, Stokes parameters, and Poincaré sphere representations of arbitrary cylindrical vector (CV) vortex beams. Then, based on the vector diffraction theory, we derive and build an integrated analytical model to calculate the electromagnetic field and Poynting vector distributions of the input CV vortex beams. The calculations reveal that a generalized CV vortex beam can generate a sharper focal spot than that of a radially polarized (RP) plane beam in the focal plane. Besides, the focal size decrease accompanies its elongation along the optical axis. Hence, it seems that there is a trade-off between the transverse and axial resolutions. In addition, under the precondition that the absolute values between polarization order and topological charge are equal, a higher-order CV vortex can also achieve a smaller focal size than an RP plane beam. Further, the intensity for the sidelobe admits a significant suppression. To give a deep understanding of the peculiar focusing properties, the magnetic field and Poynting vector distributions are also demonstrated in detail. These properties may be helpful in applications such as optical trapping and manipulation of particles and superresolution microscopy imaging.
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5
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Erlingsson SI, Bardarson JH, Manolescu A. Thermoelectric current in topological insulator nanowires with impurities. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2018; 9:1156-1161. [PMID: 29719766 PMCID: PMC5905242 DOI: 10.3762/bjnano.9.107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 03/09/2018] [Indexed: 06/08/2023]
Abstract
In this paper we consider charge current generated by maintaining a temperature difference over a nanowire at zero voltage bias. For topological insulator nanowires in a perpendicular magnetic field the current can change sign as the temperature of one end is increased. Here we study how this thermoelectric current sign reversal depends on the magnetic field and how impurities affect the size of the thermoelectric current. We consider both scalar and magnetic impurities and show that their influence on the current are quite similar, although the magnetic impurities seem to be more effective in reducing the effect. For moderate impurity concentration the sign reversal persists.
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Affiliation(s)
- Sigurdur I Erlingsson
- School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik, Iceland
| | - Jens H Bardarson
- Department of Physics, KTH Royal Institute of Technology, Stockholm, SE-106 91 Sweden
| | - Andrei Manolescu
- School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik, Iceland
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6
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Raichev OE. Nonlocality, Correlations, and Magnetotransport in a Spatially Modulated Two-Dimensional Electron Gas. PHYSICAL REVIEW LETTERS 2018; 120:146802. [PMID: 29694126 DOI: 10.1103/physrevlett.120.146802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Indexed: 06/08/2023]
Abstract
It is shown that the classical commensurability phenomena in weakly modulated two-dimensional electron systems is a manifestation of the intrinsic properties of the correlation functions describing a homogeneous electron gas in a magnetic field. The theory demonstrates the importance for consideration of nonlocal response and removes the gap between classical and quantum approaches to magnetotransport in such systems.
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Affiliation(s)
- O E Raichev
- Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Prospekt Nauki 41, 03028 Kyiv, Ukraine
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7
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Erlingsson SI, Manolescu A, Nemnes GA, Bardarson JH, Sanchez D. Reversal of Thermoelectric Current in Tubular Nanowires. PHYSICAL REVIEW LETTERS 2017; 119:036804. [PMID: 28777640 DOI: 10.1103/physrevlett.119.036804] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Indexed: 06/07/2023]
Abstract
We calculate the charge current generated by a temperature bias between the two ends of a tubular nanowire. We show that in the presence of a transversal magnetic field the current can change sign; i.e., electrons can either flow from the hot to the cold reservoir, or in the opposite direction, when the temperature bias increases. This behavior occurs when the magnetic field is sufficiently strong, such that Landau and snaking states are created, and the energy dispersion is nonmonotonic with respect to the longitudinal wave vector. The sign reversal can survive in the presence of impurities. We predict this result for core-shell nanowires, for uniform nanowires with surface states due to the Fermi level pinning, and for topological insulator nanowires.
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Affiliation(s)
- Sigurdur I Erlingsson
- School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik, Iceland
| | - Andrei Manolescu
- School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik, Iceland
| | - George Alexandru Nemnes
- University of Bucharest, Faculty of Physics, MDEO Research Center, 077125 Magurele-Ilfov, Romania
- Horia Hulubei National Institute for Physics and Nuclear Engineering, 077126 Magurele-Ilfov, Romania
| | - Jens H Bardarson
- Max-Planck-Institut für Physik komplexer Systeme, 01187 Dresden, Germany
- Department of Physics, KTH Royal Institute of Technology, Stockholm SE-106 91 Sweden
| | - David Sanchez
- Institute of Interdisciplinary Physics and Complex Systems IFISC (CSIC-UIB), E-07122 Palma de Mallorca, Spain
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8
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Qiu XJ, Cao ZZ, Cheng YF, Qin CC. Spin and valley-dependent electron transport through arrays of ferromagnet on monolayer MoS 2. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:105301. [PMID: 28075334 DOI: 10.1088/1361-648x/aa58c4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We theoretically study ballistic transport of Dirac fermions in MoS2 junction through arrays of barriers, of width [Formula: see text], in the presence of a tunable potential of height [Formula: see text] and an exchange field [Formula: see text]. The charge conductance as functions of [Formula: see text] and [Formula: see text], exhibits more conspicuous and sharpened oscillation as the number of barriers increase, due to the contribution of evanescent modes near the edges of the extremum conductance which are exponentially suppressed or enhanced. Furthermore, we found the valley-resolved conductance exhibits a similar oscillating behavior as the charge conductance for multiple barriers, but with inverse oscillatory phases for [Formula: see text] and [Formula: see text], accordingly, a high-efficiency fully valley polarized device is proposed in our system. Also, a perfect 100% spin polarized conductance is observed for 4 barriers and the polarized direction can be switched by changing the direction of exchange field. These findings not only benefit understanding of basic physics in monolayers MoS2, but also provide us a new way to generate a pure and high-efficiency spintronics and valleytronics.
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Affiliation(s)
- X J Qiu
- College of Electronics and Information, Hubei Key Laboratory of Intelligent Wireless Communications, South-Central University for Nationalities, Wuhan 430074, People's Republic of China
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9
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Jin D, Lu L, Wang Z, Fang C, Joannopoulos JD, Soljačić M, Fu L, Fang NX. Topological magnetoplasmon. Nat Commun 2016; 7:13486. [PMID: 27892453 PMCID: PMC5148233 DOI: 10.1038/ncomms13486] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/03/2016] [Indexed: 11/09/2022] Open
Abstract
Classical wave fields are real-valued, ensuring the wave states at opposite frequencies and momenta to be inherently identical. Such a particle–hole symmetry can open up new possibilities for topological phenomena in classical systems. Here we show that the historically studied two-dimensional (2D) magnetoplasmon, which bears gapped bulk states and gapless one-way edge states near-zero frequency, is topologically analogous to the 2D topological p+ip superconductor with chiral Majorana edge states and zero modes. We further predict a new type of one-way edge magnetoplasmon at the interface of opposite magnetic domains, and demonstrate the existence of zero-frequency modes bounded at the peripheries of a hollow disk. These findings can be readily verified in experiment, and can greatly enrich the topological phases in bosonic and classical systems. The two dimensional magnetoplasmon edge state has been observed for a long time, but its nature is yet to be uncovered. Here, Jin et al. report that such a state is actually topological protected, analogous to the chiral Majorana edge state in a p-wave topological superconductor.
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Affiliation(s)
- Dafei Jin
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Ling Lu
- Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China.,Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Zhong Wang
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China.,Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Chen Fang
- Institute of Physics, Chinese Academy of Sciences/Beijing National Laboratory for Condensed Matter Physics, Beijing 100190, China.,Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - John D Joannopoulos
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Marin Soljačić
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Liang Fu
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Nicholas X Fang
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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10
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Wang YL, Xiao ZL, Snezhko A, Xu J, Ocola LE, Divan R, Pearson JE, Crabtree GW, Kwok WK. Rewritable artificial magnetic charge ice. Science 2016; 352:962-6. [DOI: 10.1126/science.aad8037] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 04/13/2016] [Indexed: 11/02/2022]
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11
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Man Z, Min C, Du L, Zhang Y, Zhu S, Yuan X. Sub-wavelength sized transversely polarized optical needle with exceptionally suppressed side-lobes. OPTICS EXPRESS 2016; 24:874-882. [PMID: 26832470 DOI: 10.1364/oe.24.000874] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
It is well known that radially polarized beam could produce an ultra-long longitudinally polarized focus, referred to as "optical needle". In this work, we reveal that the counterpart transversely polarized optical needle (~5.83λ) with exceptionally suppressed sidelobes (9.9% of the maximum of the principal lobe) can be generated by tightly focusing a hybridly polarized beam through a multibelt binary phase filter. A universal analytical model is built up for investigating the depth, uniformity and polarization properties of the needle. We find that there is a trade-off between needle length and intensity uniformity, and the main lobe keeps almost transverse polarization at each observation plane. Such a nondiffraction transversely polarized optical needle has potential applications in ultrahigh density magnetic storage as well as atomic trap and switches.
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12
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Rickhaus P, Makk P, Liu MH, Tóvári E, Weiss M, Maurand R, Richter K, Schönenberger C. Snake trajectories in ultraclean graphene p-n junctions. Nat Commun 2015; 6:6470. [PMID: 25732244 PMCID: PMC4366485 DOI: 10.1038/ncomms7470] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 01/30/2015] [Indexed: 11/16/2022] Open
Abstract
Snake states are trajectories of charge carriers curving back and forth along an interface. There are two types of snake states, formed by either inverting the magnetic field direction or the charge carrier type at an interface. The former has been demonstrated in GaAs–AlGaAs heterostructures, whereas the latter has become conceivable only with the advance of ballistic graphene where a gap-less p–n interface governed by Klein tunnelling can be formed. Such snake states were hidden in previous experiments due to limited sample quality. Here we report on magneto-conductance oscillations due to snake states in a ballistic suspended graphene p–n junction, which occur already at a very small magnetic field of 20 mT. The visibility of 30% is enabled by Klein collimation. Our finding is firmly supported by quantum transport simulations. We demonstrate the high tunability of the device and operate it in different magnetic field regimes. Snake states describe electron trajectories that curve along an interface where the charge is inverted. Here, the authors investigate electronic transport in a ballistic graphene p–n junction and observe striking conductance oscillations that are a signature of these unusual states.
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Affiliation(s)
- Peter Rickhaus
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Péter Makk
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Ming-Hao Liu
- Institut für Theoretische Physik,Universität Regensburg, D-93040 Regensburg, Germany
| | - Endre Tóvári
- Department of Physics, Budapest University of Technology and Economics and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budafoki ut 8, 1111 Budapest, Hungary
| | - Markus Weiss
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
| | - Romain Maurand
- University Grenoble Alpes, CEA-INAC-SPSMS, F-38000 Grenoble, France
| | - Klaus Richter
- Institut für Theoretische Physik,Universität Regensburg, D-93040 Regensburg, Germany
| | - Christian Schönenberger
- Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland
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13
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Rosdahl TO, Manolescu A, Gudmundsson V. Signature of snaking states in the conductance of core-shell nanowires. NANO LETTERS 2015; 15:254-258. [PMID: 25426964 DOI: 10.1021/nl503499w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We model a core-shell nanowire (CSN) by a cylindrical surface of finite length. A uniform magnetic field perpendicular to the axis of the cylinder forms electron states along the lines of zero radial field projection, which can classically be described as snaking states. In a strong field, these states converge pairwise to quasidegenerate levels, which are situated at the bottom of the energy spectrum. We calculate the conductance of the CSN by coupling it to leads and predict that the snaking states govern transport at low chemical potential, forming isolated peaks, each of which may be split in two by applying a transverse electric field. If the contacts with the leads do not completely surround the CSN, as is usually the case in experiments, the amplitude of the snaking peaks changes when the magnetic field is rotated, determined by the overlap of the contacts with the snaking states.
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Affiliation(s)
- Tomas Orn Rosdahl
- School of Science and Engineering, Reykjavik University , Menntavegur 1, IS-101 Reykjavik, Iceland
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14
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Wang S, Li X, Zhou J, Gu M. Ultralong pure longitudinal magnetization needle induced by annular vortex binary optics. OPTICS LETTERS 2014; 39:5022-5025. [PMID: 25166064 DOI: 10.1364/ol.39.005022] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this Letter, based on the Richards and Wolf diffraction theory, an ultralong optical needle with pure transverse polarization is numerically generated by tightly focusing an azimuthally polarized beam through an annular vortex binary filter. Such an ultralong transversely polarized optical needle is generated through the π phase shift between adjacent rings of the binary filter. We show that such a pure transverse optical needle can induce pure longitudinal magnetization with a subwavelength lateral size (0.38λ) and an ultralong longitudinal depth (7.48λ) through the inverse Faraday effect. The corresponding needle aspect ratio of 20 is twice as large as that of the longitudinal magnetization needle generated by electron beam lithography.
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15
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Li H, Shao J, Yao D, Yang G. Gate-voltage-controlled spin and valley polarization transport in a normal/ferromagnetic/normal MoS₂ junction. ACS APPLIED MATERIALS & INTERFACES 2014; 6:1759-1764. [PMID: 24417464 DOI: 10.1021/am4047602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Two-dimensional (2D) materials are extensively explored due to the remarkable physical property and the great potential for post-silicon electronics since the landmark achievement of graphene. The monolayer (ML) MoS2 with a direct energy gap is a typical 2D material and promising candidate for a wide range of device applications. The extensive efforts so far have focused on the optical valley control applications of ML MoS2 rather than the electrical control of spin and valley transport. However, the electrical manipulation of spin injection and transport is essential to realize practical spintronics applications. Here, we theoretically demonstrated that the valley and spin transport can be electrically manipulated by a gate voltage in a normal/ferromagnetic/normal monolayer MoS2 junction device. It was found that the fully valley- and spin-polarized conductance can be achieved due to the spin-valley coupling of valence-band edges together with the exchange field, and both the amplitude and direction of the fully spin-polarized conductance can be modulated by the gate voltage. These findings not only provided deep understanding to the basic physics in the spin and valley transport of ML MoS2 but also opened an avenue for the electrical control of valley and spin transport in monolayer dichalcogenide-based devices.
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Affiliation(s)
- Hai Li
- State Key Laboratory of Optoelectronic Materials and Technologies, Institute of Optoelectronic and Functional Composite Materials, Nanotechnology Research Center, School of Physics and Engineering, Sun Yat-sen University , Guangzhou 510275, Guangdong, People's Republic of China
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16
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Kamburov D, Shayegan M, Pfeiffer LN, West KW, Baldwin KW. Commensurability oscillations of hole-flux composite fermions. PHYSICAL REVIEW LETTERS 2012; 109:236401. [PMID: 23368228 DOI: 10.1103/physrevlett.109.236401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Indexed: 06/01/2023]
Abstract
We report the observation of commensurability oscillations of hole-flux composite fermions near a filling factor of ν=1/2 in a high-mobility two-dimensional hole system confined to a GaAs quantum well and subjected to a weak, strain-induced, unidirectional periodic potential modulation. The oscillations, which are consistent with ballistic transport of fully spin-polarized composite fermions in a weak periodic effective magnetic field, are surprisingly strong and exhibit up to third-order minima. We extract a ballistic mean-free path of about 0.1 μm for the hole-flux composite fermions.
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Affiliation(s)
- D Kamburov
- Department of Electrical Engineering, Princeton University, Princeton, New Jersey 08544, USA
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17
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Lu MW, Wang ZY, Chen SY, Zhang GL. Voltage-controllable spin beam splitter based on realistic magnetic-barrier nanostructure. Micron 2012. [PMID: 23182680 DOI: 10.1016/j.micron.2012.10.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We report a theoretical investigation on the Goos-Hänchen (GH) effect of spin electron beams in realistic magnetic-barrier (MB) nanostructures under an applied voltage, which can be experimentally created by lithographic patterning of ferromagnetic (FM) or superconducting films. GH shifts of spin electron beams are calculated numerically for the InAs material system, with the help of the stationary phase method. It is shown that a significant spin polarization effect can be induced by such MB nanostructures with symmetric magnetic field profiles. It also is shown that both magnitude and sign of the spin polarization is closely relative to the electric barrier (EB) produced by a constant voltage applied to the metallic FM stripe of system. These interesting properties may provide an alternative way to spin injection into the semiconductor, and such nanostructures can serve as voltage-tunable spin beam splitters.
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Affiliation(s)
- Mao-Wang Lu
- College of Science, Guilin University of Technology, Guilin 541004, People's Republic of China.
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18
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Firoz Islam SK, Ghosh TK. Magnetotransport properties of a magnetically modulated two-dimensional electron gas with the spin-orbit interaction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2012; 24:185303. [PMID: 22481295 DOI: 10.1088/0953-8984/24/18/185303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We study the electrical transport properties of a two-dimensional electron gas (2DEG) with the Rashba spin-orbit interaction in the presence of a constant perpendicular magnetic field (B(0)( ̂z) which is weakly modulated by B1 = B1 cos(qx) ̂z, where B(1) ≪ B(0) and q = 2π/a with a the modulation period. We obtain the analytical expressions of the diffusive conductivities for spin-up and spin-down electrons. The conductivities for spin-up and spin-down electrons oscillate with different frequencies and produce beating patterns in the amplitude of the Weiss and Shubnikov-de Haas oscillations. We show that the Rashba strength can be determined by analyzing the beating pattern in the Weiss oscillation. We find a simple equation which determines the Rashba spin-orbit interaction strength if the number of Weiss oscillations between any two successive nodes is known from the experiment. We compare our results with the electrically modulated 2DEG with the Rashba interaction. For completeness, we also study the beating pattern formation in the collisional and the Hall conductivities.
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Affiliation(s)
- S K Firoz Islam
- Department of Physics, Indian Institute of Technology-Kanpur, Kanpur-208 016, India.
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19
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Wu Z, Li J. Spin-related tunneling through a nanostructured electric-magnetic barrier on the surface of a topological insulator. NANOSCALE RESEARCH LETTERS 2012; 7:90. [PMID: 22283846 PMCID: PMC3292916 DOI: 10.1186/1556-276x-7-90] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 01/27/2012] [Indexed: 05/31/2023]
Abstract
We investigate quantum tunneling through a single electric and/or magnetic barrier on the surface of a three-dimensional topological insulator. We found that (1) the propagating behavior of electrons in such system exhibits a strong dependence on the direction of the incident electron wavevector and incident energy, giving the possibility to construct a wave vector and/or energy filter; (2) the spin orientation can be tuned by changing the magnetic barrier structure as well as the incident angles and energies.PACS numbers: 72.25.Dc; 73.20.-r; 73.23.-b; 75.70.-i.
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Affiliation(s)
- Zhenhua Wu
- SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083, China
- CAE Team, Semiconductor R&D Center, Samsung Electronics Co., Ltd., Gyeonggi-Do, Korea
| | - Jun Li
- Department of Physics, Semiconductor Photonics Research Center, Xiamen University, Xiamen 361005, China
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20
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Firoz Islam SK, Singh NK, Ghosh TK. Thermodynamic properties of a magnetically modulated graphene monolayer. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:445502. [PMID: 22004991 DOI: 10.1088/0953-8984/23/44/445502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The effect of magnetic modulation on thermodynamic properties of a graphene monolayer in the presence of a constant perpendicular magnetic field is reported here. One-dimensional spatial electric or magnetic modulation lifts the degeneracy of the Landau levels and converts into bands and their bandwidth oscillates with magnetic field, leading to Weiss-type oscillations in the thermodynamic properties. The effect of magnetic modulation on the thermodynamic properties of a graphene sheet is studied and then compared with electrically modulated graphene and magnetically modulated conventional two-dimensional electron gas (2DEG). We observe Weiss-type and de Haas-van Alphen oscillations at low and high magnetic fields, respectively. There is a definite phase difference in Weiss-type oscillations in thermodynamic quantities of magnetically modulated graphene compared to electrically modulated graphene. On the other hand, the phase remains the same and the amplitude of the oscillation is large when compared with the magnetically modulated two-dimensional electron gas (2DEG). Explicit asymptotic expressions of the density of states and the Helmholtz free energy are provided to understand the phase and amplitude of the Weiss-type oscillations qualitatively. We also study thermodynamic properties when both electric and magnetic modulations are present. The Weiss-type oscillations still exist when the modulations are out-of-phase.
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Affiliation(s)
- S K Firoz Islam
- Department of Physics, Indian Institute of Technology-Kanpur, Kanpur 208 016, India
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21
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Ramezani Masir M, Vasilopoulos P, Peeters FM. Graphene in inhomogeneous magnetic fields: bound, quasi-bound and scattering states. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:315301. [PMID: 21757800 DOI: 10.1088/0953-8984/23/31/315301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The electron states in graphene-based magnetic dot and magnetic ring structures and combinations of both are investigated. The corresponding spectra are studied as a function of the radii, the strengths of the inhomogeneous magnetic field and of a uniform background field, the strength of an electrostatic barrier and the angular momentum quantum number. In the absence of an external magnetic field we have only long-lived quasi-bound and scattering states and we assess their influence on the density of states. In addition, we consider elastic electron scattering by a magnetic dot, whose average B vanishes, and show that the Hall and longitudinal resistivities, as a function of the Fermi energy, exhibit a pronounced oscillatory structure due to the presence of quasi-bound states. Depending on the dot parameters this oscillatory structure differs substantially for energies below and above the first Landau level.
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Affiliation(s)
- M Ramezani Masir
- Departement Fysica, Universiteit Antwerpen Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
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22
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Milpas E, Torres M, Murguía G. Magnetic field barriers in graphene: an analytically solvable model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:245304. [PMID: 21628785 DOI: 10.1088/0953-8984/23/24/245304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We study the dynamics of carriers in graphene subjected to an inhomogeneous magnetic field. For a magnetic field with a hyperbolic profile the corresponding Dirac equation can be analyzed within the formalism of supersymmetric quantum mechanics, and leads to an exactly solvable model. We study in detail the bound-state spectrum. For a narrow barrier the spectrum is characterized by a few bands, except for the zero energy level that remains degenerated. As the width of the barrier increases we can track the band's evolution into the degenerated Landau levels. In the scattering regime a simple analytical formula is obtained for the transmission coefficient, this result allows us to identify the resonant conditions at which the barrier becomes transparent.
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Affiliation(s)
- Enrique Milpas
- Instituto de Física, Universidad Nacional Autónoma de México, México Distrito Federal, Mexico
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23
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Nogaret A. Electron dynamics in inhomogeneous magnetic fields. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:253201. [PMID: 21393794 DOI: 10.1088/0953-8984/22/25/253201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This review explores the dynamics of two-dimensional electrons in magnetic potentials that vary on scales smaller than the mean free path. The physics of microscopically inhomogeneous magnetic fields relates to important fundamental problems in the fractional quantum Hall effect, superconductivity, spintronics and graphene physics and spins out promising applications which will be described here. After introducing the initial work done on electron localization in random magnetic fields, the experimental methods for fabricating magnetic potentials are presented. Drift-diffusion phenomena are then described, which include commensurability oscillations, magnetic channelling, resistance resonance effects and magnetic dots. We then review quantum phenomena in magnetic potentials including magnetic quantum wires, magnetic minibands in superlattices, rectification by snake states, quantum tunnelling and Klein tunnelling. The third part is devoted to spintronics in inhomogeneous magnetic fields. This covers spin filtering by magnetic field gradients and circular magnetic fields, electrically induced spin resonance, spin resonance fluorescence and coherent spin manipulation.
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Affiliation(s)
- Alain Nogaret
- Department of Physics, University of Bath, Bath, UK.
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24
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McNeil RPG, Schneble RJ, Kataoka M, Ford CJB, Kasama T, Dunin-Borkowski RE, Feinberg JM, Harrison RJ, Barnes CHW, Tse DHY, Trypiniotis T, Bland JAC, Anderson D, Jones GAC, Pepper M. Localized magnetic fields in arbitrary directions using patterned nanomagnets. NANO LETTERS 2010; 10:1549-1553. [PMID: 20377235 DOI: 10.1021/nl902949v] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Control of the local magnetic fields desirable for spintronics and quantum information technology is not well developed. Existing methods produce either moderately small local fields or one field orientation. We present designs of patterned magnetic elements that produce remanent fields of 50 mT (potentially 200 mT) confined to chosen, submicrometer regions in directions perpendicular to an external initializing field. A wide variety of magnetic-field profiles on nanometer scales can be produced with the option of applying electric fields, for example, to move a quantum dot between regions where the magnetic-field direction or strength is different. We have confirmed our modeling by measuring the fields in one design using electron holography.
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25
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Tarasov A, Hugger S, Xu H, Cerchez M, Heinzel T, Zozoulenko IV, Gasser-Szerer U, Reuter D, Wieck AD. Quantized magnetic confinement in quantum wires. PHYSICAL REVIEW LETTERS 2010; 104:186801. [PMID: 20482195 DOI: 10.1103/physrevlett.104.186801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Indexed: 05/29/2023]
Abstract
Ballistic quantum wires are exposed to longitudinal profiles of perpendicular magnetic fields composed of a spike and a homogeneous part. An asymmetric magnetoconductance peak as a function of the homogeneous magnetic field is found, comprising quantized conductance steps in the interval where the homogeneous magnetic field and the magnetic barrier have identical polarities, and a characteristic shoulder with several resonances in the interval of opposite polarities. The observations are interpreted in terms of inhomogeneous diamagnetic shifts of the quantum wire modes leading to magnetic confinement.
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Affiliation(s)
- A Tarasov
- Condensed Matter Physics Laboratory, Heinrich-Heine-Universität, Universitätsstrasse 1, 40225 Düsseldorf, Germany
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26
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Nasir R, Khan MA, Tahir M, Sabeeh K. Thermodynamic properties of a weakly modulated graphene monolayer in a magnetic field. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:025503. [PMID: 21386257 DOI: 10.1088/0953-8984/22/2/025503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Theoretical investigation of thermodynamic properties of an electrically modulated graphene monolayer in the presence of a perpendicular magnetic field B is presented. This work is aimed at determining the modulation-induced effects on the thermodynamic properties of graphene. The results obtained are compared with those of conventional two-dimensional electron gas (2DEG) systems realized in semiconductor heterostructures. The one-dimensional periodic potential, due to electric modulation lifts the degeneracy of the Landau levels and converts them into bands whose width oscillates as a function of B. We find commensurability (Weiss) oscillations for small values of B and de Haas-van Alphen (dHvA)-type oscillations at larger values of B. We find that the modulation-induced effects on the thermodynamic properties are enhanced and less damped with temperature in graphene compared with conventional 2DEG systems. Furthermore, we have derived analytic asymptotic expressions which allow us to determine the critical temperature and critical magnetic field for the damping of magnetic oscillations in the thermodynamic quantities considered here.
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Affiliation(s)
- R Nasir
- Department of Physics, Quaid-i-Azam University, Islamabad 45320, Pakistan
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27
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Tahir M, Sabeeh K, MacKinnon A. The magnetoplasmon spectrum of a weakly modulated two-dimensional electron gas system. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:015801. [PMID: 21386234 DOI: 10.1088/0953-8984/22/1/015801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The magnetoplasmon spectrum of a magnetically modulated two-dimensional electron gas (2DEG) is investigated. We derive the inter- and intra-Landau-band magnetoplasmon spectrum within the self-consistent field approach. The derivation is performed at zero temperature as well as at finite temperature. Results are presented for the inter- and intra-Landau-band magnetoplasmon spectrum as a function of the inverse magnetic field. Magnetic Weiss oscillations are found to occur in the magnetoplasmon spectrum as a result of magnetic modulation. Furthermore, our finite temperature theory facilitates the analysis of effects of temperature on the magnetoplasmon spectrum. The results are compared with those obtained for an electrically modulated 2DEG system. In addition, we derive and discuss the effects of simultaneous electric and magnetic modulations on the magnetoplasmon spectrum of the 2DEG when the modulations are in phase as well as when they are out of phase. Magnetic oscillations are affected by the relative phase of the two modulations and the position of the oscillations depends on the relative strength of the two modulations in the former case while we find complete suppression of Weiss oscillations for a particular relative strength of the modulations in the latter case.
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Affiliation(s)
- M Tahir
- Department of Physics, Blackett Laboratory, Imperial College London, South Kensington Campus, London, UK.
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28
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Polushkin NI. Combined electron resonance driven by an all-oscillating potential of patterned magnets. PHYSICAL REVIEW LETTERS 2009; 103:077201. [PMID: 19792679 DOI: 10.1103/physrevlett.103.077201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2009] [Indexed: 05/28/2023]
Abstract
A novel mechanism is proposed for the phenomenon of combined electron resonance. It is shown that the spatially localized microwave fields of an Fe stripe array mediate the intense electronic transitions involving the changes in both spin and orbital quantum numbers when the electron moves along a cyclotron orbit in a semiconductor (e.g., InGaAs-based) quantum well. This discovery bridges the fields of spintronics and quantum computing, paving the way for conceptually new hybrid devices based on ferromagnetic and semiconductor structured materials.
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Affiliation(s)
- Nikolay I Polushkin
- Institute for Physics of Microstructures of Russian Academy of Sciences, 603950 GSP-105 Nizhniy Novgorod, Russian Federation.
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29
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Nogaret A, Portal JC, Beere HE, Ritchie DA, Phillips C. Quantum interference of magnetic edge channels activated by intersubband optical transitions in magnetically confined quantum wires. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:025303. [PMID: 21813973 DOI: 10.1088/0953-8984/21/2/025303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
We investigate the photoresistance of a magnetically confined quantum wire in which microwave-coupled edge channels interfere at two pinning sites in the fashion of a Mach-Zehnder interferometer. The conductance is strongly enhanced by microwave power at B = 0 and develops a complex series of oscillations when the magnetic confinement increases. Both results are quantitatively explained by the activation of forward scattering in a multimode magnetically confined quantum wire. By varying the strength of the magnetic confinement we are able to tune the phase of electrons in the arms of the interferometer. Quantum interferences which develop between pinning sites explain the oscillations of the conductance as a function of the magnetic field. A fit of the data gives the distance between pinning sites as 11 µm. This result suggests that quantum coherence is conserved over a distance three times longer than the electron mean free path.
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Affiliation(s)
- A Nogaret
- Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK
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30
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Soskin SM, Mannella R, Yevtushenko OM. Matching of separatrix map and resonant dynamics, with application to global chaos onset between separatrices. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2008; 77:036221. [PMID: 18517499 DOI: 10.1103/physreve.77.036221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2006] [Revised: 10/10/2007] [Indexed: 05/26/2023]
Abstract
We have developed a general method for the description of separatrix chaos, based on the analysis of the separatrix map dynamics. Matching it with the resonant Hamiltonian analysis, we show that, for a given amplitude of perturbation, the maximum width of the chaotic layer in energy may be much larger than it was assumed before. We use the above method to explain the drastic facilitation of global chaos onset in time-periodically perturbed Hamiltonian systems possessing two or more separatrices, previously discovered [S. M. Soskin, O. M. Yevtushenko, and R. Mannella, Phys. Rev. Lett. 90, 174101 (2003)]. The theory well agrees with simulations. We also discuss generalizations and applications. The method may be generalized for single-separatrix cases. The facilitation of global chaos onset may be relevant to a variety of systems, e.g., optical lattices, magnetic and semiconductor superlattices, meandering flows in the ocean, and spinning pendulums. Apart from dynamical transport, it may facilitate noise-induced transitions and the stochastic web formation.
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Affiliation(s)
- S M Soskin
- Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev, Ukraine
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31
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De Martino A, Dell'Anna L, Egger R. Magnetic confinement of massless Dirac fermions in graphene. PHYSICAL REVIEW LETTERS 2007; 98:066802. [PMID: 17358966 DOI: 10.1103/physrevlett.98.066802] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Indexed: 05/14/2023]
Abstract
Because of Klein tunneling, electrostatic potentials are unable to confine Dirac electrons. We show that it is possible to confine massless Dirac fermions in a monolayer graphene sheet by inhomogeneous magnetic fields. This allows one to design mesoscopic structures in graphene by magnetic barriers, e.g., quantum dots or quantum point contacts.
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Affiliation(s)
- A De Martino
- Institut für Theoretische Physik, Heinrich-Heine-Universität, D-40225 Düsseldorf, Germany
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32
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Nogaret A. Electrically induced Raman emission from planar spin oscillator. PHYSICAL REVIEW LETTERS 2005; 94:147207. [PMID: 15904105 DOI: 10.1103/physrevlett.94.147207] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2004] [Indexed: 05/02/2023]
Abstract
We predict that two-dimensional electrons confined by a magnetic field gradient resonantly transfer energy to the electromagnetic field by a process of inverse electron spin resonance that is realized when the frequency of an open orbit equals the Larmor frequency. The calculated emission spectra show multiple peaks modulated by strong optical nonlinearities whose frequencies may be tuned by the magnetic field gradient and the electron concentration.
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Affiliation(s)
- A Nogaret
- Department of Physics, University of Bath, Claverton Down, Bath, BA2 7AY, United Kingdom.
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33
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Soskin SM, Yevtushenko OM, Mannella R. Drastic facilitation of the onset of global chaos. PHYSICAL REVIEW LETTERS 2003; 90:174101. [PMID: 12786071 DOI: 10.1103/physrevlett.90.174101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2002] [Indexed: 05/24/2023]
Abstract
We show that the onset of global chaos in a time periodically perturbed Hamiltonian system may occur at unusually small magnitudes of perturbation if the unperturbed system possesses more than one separatrix. The relevant scenario is the combination of the overlap in the phase space between resonances of the same order and their overlap in energy with chaotic layers associated with separatrices of the unperturbed system. We develop the asymptotic theory and verify it in simulations.
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Affiliation(s)
- S M Soskin
- Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Kiev
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34
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Frustaglia D, Hentschel M, Richter K. Quantum transport in nonuniform magnetic fields: Aharonov-Bohm ring as a spin switch. PHYSICAL REVIEW LETTERS 2001; 87:256602. [PMID: 11736592 DOI: 10.1103/physrevlett.87.256602] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2001] [Indexed: 05/23/2023]
Abstract
We study spin-dependent magnetoconductance in mesoscopic rings subject to an inhomogeneous in-plane magnetic field. We show that the polarization direction of transmitted spin-polarized electrons can be controlled via an additional magnetic flux such that spin flips are induced at half a flux quantum. This quantum interference effect is independent of the strength of the nonuniform field applied. We give an analytical explanation for one-dimensional rings and numerical results for corresponding ballistic microstructures.
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Affiliation(s)
- D Frustaglia
- Max-Planck-Institut für Physik komplexer Systeme, Nöthnitzer Strasse 38, 01187 Dresden, Germany
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35
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Sim HS, Ihm G, Kim N, Chang KJ. Magnetic quantum dot: a magnetic transmission barrier and resonator. PHYSICAL REVIEW LETTERS 2001; 87:146601. [PMID: 11580664 DOI: 10.1103/physrevlett.87.146601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2001] [Indexed: 05/23/2023]
Abstract
We study the ballistic edge-channel transport in quantum wires with a magnetic quantum dot, which is formed by two different magnetic fields B(*) and B0 inside and outside the dot, respectively. We find that the electron states located near the dot and the scattering of edge channels by the dot strongly depend on whether B(*) is parallel or antiparallel to B0. For parallel fields, two-terminal conductance as a function of channel energy is quantized except for resonances, while, for antiparallel fields, it is not quantized and all channels can be completely reflected in some energy ranges. All these features are attributed to the characteristic magnetic confinements caused by nonuniform fields.
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Affiliation(s)
- H S Sim
- Department of Physics, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea
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36
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Nogaret A, Bending SJ, Henini M. Resistance resonance effects through magnetic edge states. PHYSICAL REVIEW LETTERS 2000; 84:2231-2234. [PMID: 11017251 DOI: 10.1103/physrevlett.84.2231] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/1999] [Indexed: 05/23/2023]
Abstract
We report on the magnetoresistance of a two-dimensional electron gas subjected to an abrupt magnetic field gradient arising from a ferromagnetic stripe fabricated at its surface. A sharp resistance resonance effect is observed at B(p) due to the formation of two types of magnetic edge states that drift in opposite directions perpendicular to the magnetic field gradient for B<B(p) and B>B(p). A semiclassical drift-diffusion model gives a good description of the effects of the magnetic confinement on both the diagonal and off-diagonal components of the resistivity tensor.
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Affiliation(s)
- A Nogaret
- Department of Physics, University of Bath, Bath BA2 7AY, UK
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37
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Majumdar A. Effects of intrinsic spin on electronic transport through magnetic barriers. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:11911-11913. [PMID: 9985028 DOI: 10.1103/physrevb.54.11911] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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38
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Ji ZL, Sprung DW. Electronic transport in quantum wires in nonuniform magnetic fields. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:8044-8048. [PMID: 9984482 DOI: 10.1103/physrevb.54.8044] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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39
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Kim CS, Olendski O. Landau levels and persistent currents in nonuniform magnetic fields. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:12917-12928. [PMID: 9982966 DOI: 10.1103/physrevb.53.12917] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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40
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Gusev GM, Gennser U, Kleber X, Maude DK, Portal JC, Lubyshev DI, Basmaji P, Silva M, Rossi JC, Nastaushev YV. Quantum interference effects in a strongly fluctuating magnetic field. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:13641-13644. [PMID: 9983110 DOI: 10.1103/physrevb.53.13641] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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41
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Gerhardts RR. Quasiclassical calculation of magnetoresistance oscillations of a two-dimensional electron gas in spatially periodic magnetic and electrostatic fields. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:11064-11075. [PMID: 9982679 DOI: 10.1103/physrevb.53.11064] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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42
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Gerhardts RR, Pfannkuche D, Gudmundsson V. Hofstadter-type energy spectra in lateral superlattices defined by periodic magnetic and electrostatic fields. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:9591-9594. [PMID: 9982508 DOI: 10.1103/physrevb.53.9591] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Krakovsky A. Electronic band structure in a periodic magnetic field. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:8469-8472. [PMID: 9982350 DOI: 10.1103/physrevb.53.8469] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Brown D, Band YB, Avishai Y. Magnetoresistance of two-dimensional mesoscopic structures: A variational approach. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:4855-4869. [PMID: 9984048 DOI: 10.1103/physrevb.53.4855] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Braun HB, Loss D. Berry's phase and quantum dynamics of ferromagnetic solitons. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 53:3237-3255. [PMID: 9983832 DOI: 10.1103/physrevb.53.3237] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Ibrahim IS, Peeters FM. Two-dimensional electrons in lateral magnetic superlattices. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:17321-17334. [PMID: 9981162 DOI: 10.1103/physrevb.52.17321] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Gumbs G, Miessein D, Huang D. Effect of magnetic modulation on Bloch electrons on a two-dimensional square lattice. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:14755-14760. [PMID: 9980813 DOI: 10.1103/physrevb.52.14755] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Foden CL, Leadbeater ML, Pepper M. Quantum magnetic confinement and transport in spherical two-dimensional electron gases. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:R8646-R8649. [PMID: 9979916 DOI: 10.1103/physrevb.52.r8646] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Leadbeater ML, Foden CL, Burroughes JH, Pepper M, Burke TM, Wang LL, Grimshaw MP, Ritchie DA. Magnetotransport in a nonplanar two-dimensional electron gas. PHYSICAL REVIEW. B, CONDENSED MATTER 1995; 52:R8629-R8632. [PMID: 9979911 DOI: 10.1103/physrevb.52.r8629] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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