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排序方式: 共有193条查询结果,搜索用时 15 毫秒
91.
92.
Rock‐salt chalcogenide SnTe represents the simplest realization of a topological insulator where a crystal symmetry allows for the appearance of surface metallic states. Here, we theoretically predict that strain, as realized in thin films grown on (001) substrates, may induce a transition to a topological crystalline insulating phase in related lead‐salt chalcogenides. Furthermore, relevant topological properties of the surface states, such as the location of the Dirac cones on the surface Brillouin zone or the decay length of edge states, appear to be tunable with strain, with potential implications for technological devices benefiting from those additional degrees of freedom. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
93.
Müchler L Zhang H Chadov S Yan B Casper F Kübler J Zhang SC Felser C 《Angewandte Chemie (International ed. in English)》2012,51(29):7221-7225
Heavy stuff: Topological insulators are formed of heavy atoms and host special surface or edge states. The electronic structure is characterized by a Dirac cone within a bulk band gap (see picture) that is generated by strong spin-orbit coupling. A chemist's perspective in terms of bonds, bands, symmetry, and nuclear charge is provided. 相似文献
94.
One-dimensional Mott-Hubbard insulators like Sr2CuO3, halogen-bridged Nickel chain compounds have orders-of-magnitude nonlinear optical properties compared to other one-dimensional organic or inorganic compounds. We show theoretically, that the stimulated Raman scattering susceptibility for such insulators could be order(s)-of-magnitude larger even compared to other nonlinear optical susceptibilities. The lowest two-photon state is at lower energy than the lowest one-photon state in some of these insulators. This leads to a potential for strong Stokes generation in the THz regime from these compounds. Our results and conclusions are based on exact numerical solution of finite size two-band extended Hubbard model. 相似文献
95.
Empty f-states several eV above the Fermi level may be of no interest, but they can be populated by optical means. However, when they are within thermal energy of the Fermi level, they can be populated at elevated temperatures and thus permit valence changes. We are investigating with various types of measurements, such as optical reflectivity, magneto-optics, photoemission, inverse photoemission, magnetic susceptibility, electrical resistivity and more such materials as LaS, LaSe, LaTe, CeO2, CeF4, YbN, TmS, Ce3Bi4Pt3, Ce3Sb4Pt3, and U3Sb4Pt3. Some of these materials are superconductors, insulators, semimetals, metals, Kondo insulators or semiconductors. 相似文献
96.
K. Gnanasekar K. Navaneethakrishnan 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(4):455-461
Spin-dependent Floquet scattering theory is developed to investigate the
photon-assisted spin-polarized electron transport through a semiconductor
heterostructure in the presence of an external electric field.
Spin-dependent Fano resonances and spin-polarized electron transport through
a laser irradiated time-periodic non-magnetic heterostructure in the
presence of Dresselhaus spin-orbit interaction and a gate-controlled Rashba
spin-orbit interaction are investigated. The electric field due to laser
along with the spin-orbit interactions help to get spin-dependent Fano
resonances in the conductance, whereas the external bias can be
appropriately adjusted to get a near 80% spin-polarized electron
transmission through heterostructures. The resultant nature of the Floquet
scattering depends on the relative strength of these two electric fields. 相似文献
97.
R. Balian J.-J. Niez 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,2(4):413-449
When an electromagnetic wave impinges on a semiconductor or ionic conductor having a sizeable screening length, it induces
diffusion currents in addition to the ohmic currents, which affects the propagation in heterostructures or composite media
involving such materials. In the simple geometries and in the low frequency regime studied here, the absorption may be either
enhanced or reduced, depending on the parameters, and effects precluded for metals are predicted: extinction of the reflection
by a plane wall, complete absorption of an electric multipolar wave by a sphere, disappearance of the scattering by a small
sphere, vanishing of both reflection and transmission coefficients for a slab. If the screening length is larger than the
skin depth, a slab with intermediate thickness may have a large transparency, and a thick piece of material is expected to
be cooled down by the wave near the interface and overheated deeper inside.
Received: 29 July 1997 / Revised: 24 November 1997 / Accepted: 20 February 1998 相似文献
98.
Piet Schönherr Shilei Zhang Yuanqian Liu Patryk Kusch Stephanie Reich Terence Giles Dominik Daisenberger Dharmalingam Prabhakaran Yulin Chen Thorsten Hesjedal 《固体物理学:研究快报》2015,9(2):130-135
A novel topological insulator with orthorhombic crystal structure is demonstrated. It is characterized by quasi one‐dimensional, conducting atomic chains instead of the layered, two‐dimensional sheets known from the established Bi2(Se,Te)3 system. The Sb‐doped Bi2Se3 nanowires are grown in a TiO2‐catalyzed process by chemical vapor deposition. The binary Bi2Se3 is transformed from rhombohedral to orthorhombic by substituting Sb on ~38% of the Bi sites. Pure Sb2Se3 is a topologically trivial band insulator with an orthorhombic crystal structure at ambient conditions, and it is known to transform into a topological insulator at high pressure. Angle‐resolved photoemission spectroscopy shows a topological surface state, while Sb doping also tunes the Fermi level to reside in the bandgap. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
99.
Magnetic proximity effects can lead to novel phenomena in the transport properties of topological insulators. In this study, we demonstrate a characteristic fourfold symmetry in the angular dependence of magnetoresistance in the topological insulator BiSbTeSe2 exfoliated onto magnetic insulator yttrium iron garnet substrates. The observed symmetry is seen to arise when the external magnetic field is in‐plane to the current direction and gets enhanced at large field magnitudes. Increasing the temperature and current density diminishes the fourfold symmetry. The symmetry seems to be a signature of the proximity effect from the underlying magnetic substrate on BiSbTeSe2. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
100.
A. Nossov J. Pierre J. Beille V. Vassiliev B. Slobodin 《The European Physical Journal B - Condensed Matter and Complex Systems》1998,6(4):467-472
The influence of hydrostatic pressure on the transport properties of (La1-xRx)0.67Ca0.33MnO3 (,Tb) ferromagnetic manganites is investigated. The enhancement of the Curie temperature TC under pressure agrees with previous data. In the paramagnetic range, the resistivity can be represented by a Mott localisation
law, with a characteristic temperature T0 decreasing with pressure. The variation of TC with pressure is compared to the effect induced by replacing La by a magnetic rare earth in (La1-xRx)0.67Sr0.33MnO3 manganites (, ..., Tm). The main effect is not related to the decrease of the mean radius of the cation, but to an additional scattering
by the magnetic moment of the rare earth.
Received: 15 May 1998 / Revised: 6 July 1998 / Accepted: 16 July 1998 相似文献