共查询到20条相似文献,搜索用时 31 毫秒
1.
Zhongshui Ma 《Solid State Communications》2010,150(11-12):510-513
We predict an intrinsic thermo-spin Hall effect, namely, that a transverse spin current is generated by the temperature gradient and the heat current in a disorder-free two-dimensional electron gas (2DEG) with finite spin–orbit coupling. There exist two classes of contributions to the thermal spin Hall effect, corresponding to a 2DEG contacting two reservoirs at different temperatures and to a 2DEG separated from the reservoirs by insulating spacers, respectively. It is shown that the thermal spin Hall current can be generated not only by the temperature gradient directly but also by the thermoelectric effect. 相似文献
2.
Karmakar B Venturelli D Chirolli L Taddei F Giovannetti V Fazio R Roddaro S Biasiol G Sorba L Pellegrini V Beltram F 《Physical review letters》2011,107(23):236804
We introduce and experimentally demonstrate a new method that allows us to controllably couple copropagating spin-resolved edge states of a two-dimensional electron gas (2DEG) in the integer quantum Hall regime. The scheme exploits a spatially periodic in-plane magnetic field that is created by an array of Cobalt nanomagnets placed at the boundary of the 2DEG. A maximum charge or spin transfer of 28±1% is achieved at 250 mK. 相似文献
3.
We report a theoretic study on modulating the spin polarization of charge current in a mesoscopic four-terminal device of cross structure by using the inverse spin hall effect. The scattering region of device is a two-dimensional electron gas (2DEG) with Rashba spin orbital interaction (RSOI), one of lead is ferromagnetic metal and other three leads are spin-degenerate normal metals. By using Landauer-Büttiker formalism, we found that when alongitudinal charge current flows through 2DEG scattering region from FM lead by external bias, the transverse current can be either a pure spin current or full-polarized charge current due to the combined effect of spin hall effect and its inverse process, and the polarization of this transverse current can be easily controlled by several device parameters such as the Fermi energy, ferromagnetic magnetization, and the RSOI constant. Our method may pave a new way to control the spin polarization of a charge current. 相似文献
4.
通过分析不同温度下HgMnTe磁性二维电子气Shubnikov-de Hass(SdH)振荡的拍频现象,研究了量子阱中电子自旋 轨道相互作用和spd交换相互作用.结果表明:(1)在零磁场下,电子的自旋 轨道相互作用导致电子发生零场自旋分裂;(2)在弱磁场下,电子的自旋-轨道相互作用占主导地位,并受Landau分裂和Zeeman分裂的影响,电子的自旋分裂随磁场增加而减小;(3)在高磁场下,电子的spd交换相互作用达到饱和,电子的自旋分裂主要表现为Zeeman分裂.实验证明了当电子的Zeeman分裂能量与零场
关键词:
磁性二维电子气
Zeeman分裂
Rashba自旋分裂 相似文献
5.
We obtain analytic formulas for the frequency-dependent spin-Hall conductivity of a two-dimensional electron gas (2DEG) in the presence of impurities, linear spin-orbit Rashba interaction, and external magnetic field perpendicular to the 2DEG. We show how different mechanisms (skew scattering, side jump, and spin precession) can be brought in or out of focus by changing controllable parameters such as frequency, magnetic field, and temperature. We find, in particular, that the dc spin-Hall conductivity vanishes in the absence of a magnetic field, while a magnetic field restores the skew-scattering and side jump contributions proportionally to the ratio of magnetic and Rashba fields. 相似文献
6.
S. Bellucci P. Onorato 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):35-40
We propose a new scheme of spin filtering employing ballistic
nanojunctions patterned in a two dimensional electron gas
(2DEG). Our proposal is essentially based on the spin-orbit (SO)
interaction generated by a lateral confining potential (β-SO
coupling ).
We demonstrate that the flow of a longitudinal unpolarized current
through a ballistic T and X junction with this spin-orbit
coupling will induce a spin accumulation which has opposite signs
for the two lateral probes and is, therefore, the principal
observable signature of the spin Hall effect in these devices. 相似文献
7.
King PD He RH Eknapakul T Buaphet P Mo SK Kaneko Y Harashima S Hikita Y Bahramy MS Bell C Hussain Z Tokura Y Shen ZX Hwang HY Baumberger F Meevasana W 《Physical review letters》2012,108(11):117602
We demonstrate the formation of a two-dimensional electron gas (2DEG) at the (100) surface of the 5d transition-metal oxide KTaO3. From angle-resolved photoemission, we find that quantum confinement lifts the orbital degeneracy of the bulk band structure and leads to a 2DEG composed of ladders of subband states of both light and heavy carriers. Despite the strong spin-orbit coupling, our measurements provide a direct upper bound for the potential Rashba spin splitting of only Δk(parallel)}~0.02 ?(-1) at the Fermi level. The polar nature of the KTaO3(100) surface appears to help mediate the formation of the 2DEG as compared to nonpolar SrTiO3(100). 相似文献
8.
We consider a two-dimensional electron gas (2DEG) with the Rashba spin-orbit interaction (SOI) in the presence of a perpendicular magnetic field. We derive analytical expressions of the density of states (DOS) of a 2DEG with the Rashba SOI in the presence of a magnetic field by using the Green's function technique. The DOS allows us to obtain the analytical expressions of the magnetoconductivities for spin-up and spin-down electrons. The conductivities for spin-up and spin-down electrons oscillate with different frequencies and give rise to the beating patterns in the amplitude of the Shubnikov-de Haas (SdH) oscillations. We find a simple equation which determines the zero-field spin splitting energy if the magnetic field corresponding to any beat node is known from the experiment. Our analytical results reproduce well the experimentally observed non-periodic beating patterns, number of oscillations between two successive nodes and the measured zero-field spin splitting energy. 相似文献
9.
《Physics letters. A》2020,384(14):126283
Despite of extensive researches about oxide heterointerfaces, preparing method and intrinsic mechanism are all challenging topics. Here, we generate a series of stable quasi two dimensional electron gases (q-2DEGs) at yttrium aluminum oxides/strontium titanate (YAO/STO) heterointerfaces by the spin coating for the first time. It is found that the thickness and the stoichiometry ratio are the key factors for the creation of q-2DEG, which is formed under the premise of thickness (about 81.1 ∼ 356.4 nm) and the rich-Al (Al:Y≥1:1). The underlying mechanism can be attributed to oxygen vacancies derived from the redox reaction between YAO film and STO substrate. In addition, the conductive behavior can be modulated by the light illumination and the value of photoinduced change reaches 153.7% at low temperature. This work paves a novel way to fabricate 2DEG massively and helpful for a deep understanding about the conductive mechanism of oxide heterostructures. 相似文献
10.
J. J. Zhang F. Liang J. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,72(1):105-112
Using the Keldysh Green’s function method, we study theoretically the electron accumulation induced by the inverse spin Hall
effect in a spin valve structure in which a clean quantum wire formed from a 2D electron gas (2DEG) with Rashba/Dresselahaus
spin orbit interaction (SOI) is connected to two ferromagnet electrodes. In a nonequilibrium situation when a spin current
with an out-of plane (the 2DEG plane) spin polarization is driven through the SOI region by an external voltage, non-equilibrium
electron accumulation or a Hall voltage forms at the two lateral sides of the quantum wire and exhibits an oscillation along
the wire like the Rashba spin precession; the magnetization directions of FMs affect the Hall voltage and their parallel or
antiparallel alignment along the normal direction of the 2DEG plane is most favorable to the Hall voltage. In an equilibrium
situation, two planar magnetizations which are not collinear can generate an electron accumulation/a Hall voltage too. When
one of the FM electrodes is replaced by a normal metal (NM), the electron accumulation is still present along the wire and
its magnitude remains nearly unchanged in the biased case, whereas in the unbiased case it is reduced significantly and even
vanishes. 相似文献
11.
Maowang Lu Lide Zhang Yunxia Jin Xiaohong Yan 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(4):565-570
We study the spin-dependent transport properties of the nanostructures consisting of realistic magnetic barriers produced
by the deposition of ferromagnetic stripes on heterostructures. It is shown that, only in the nanostructures with symmetric
magnetic field with respect to the magnetic-modulation direction, electrons exhibit a considerable spin-polarization. It is
also shown that the degree of the electron spin polarization is greatly dependent on the ferromagnetic stripe and its position
relative to the 2DEG. A much larger electron-spin polarization can be obtained by properly fabricating the ferromagnetic stripe
and by adjusting its distance above the 2DEG.
Received 27 December 2001 and Received in final form 13 March 2002 Published online 25 June 2002 相似文献
12.
The Bloch spinors, energy spectrum, and spin density in energy bands are studied for a two-dimensional electron gas (2DEG)
with Rashba spin-orbit (SO) interaction subject to the one-dimensional (1D) periodic electrostatic potential of a lateral
superlattice. The space symmetry of the Bloch spinors with spin parity is studied. It is shown that the Bloch spinors at fixed
quasi-momentum describe the standing spin waves with the wavelength equal to the superlattice period. The spin projections
in these states have components both parallel and transverse to the 2DEG plane. The anticrossing of the energy dispersion
curves due to the interplay between the SO and periodic terms is observed, thus, leading to the spin flip. The relation between
the spin parity and the interband optical selection rules is discussed, and the effect of magnetization of the SO superlattice
in the presence of an external electric field is predicted.
The text was submitted by the authors in English. 相似文献
13.
W. Xu Z. Zeng F. Lu C. Zhang 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):272
We examine how the Rashba spin-orbit interaction (SOI) affects the fast-electron optical spectrum of a two-dimensional electron gas (2DEG). It is found that for a spin-split 2DEG, the spectrum of optical absorption is mainly induced by plasmon excitation via inter-SO electronic transition. From the width and position of the spectrum, the Rashba spin-splitting can be identified optically and, therefore, important spintronic properties can be measured though optical experiments. 相似文献
14.
Y. ItoY. Teraoka 《Solid State Communications》2003,127(4):275-278
Using spin density functional theory within the framework of the local spin density approximation with Perdew-Zunger type exchange-correlation energy, ferromagnetism in a quasi-two-dimensional electron gas (Q-2DEG) is studied. The electronic and magnetic structures of a thin film are calculated as a function of film thickness and electron density. Ferromagnetism in the Q-2DEG is found to appear at a higher electron density than in the three-dimensional electron gas. Unless a film is very thin, with decreasing electron density, a magnetic phase transition occurs from a spin-unpolarized fluid to a Wigner film with surface magnetism, in which the spin polarization localizes only in the neighborhood of surfaces. Further decreasing density induces another transition to a fully spin-polarized ferromagnetic Wigner film. 相似文献
15.
The spin-dependent mean-free path of electrons in a high-mobility InAs two-dimensional electron gas (2DEG) is measured. Ferromagnetic metal/insulator/2DEG junctions are fabricated on a common channel in a nonlocal geometry and used as spin injectors and detectors. For electrons in spin-orbit eigenstates at 4.5 K, lower bounds for the spin mean-free path and relaxation time are Lambda(S) > or = 4.6 microm and tau(s) > or = 3.8 ps, respectively. The temperature dependence is weak over the range 4.5相似文献
16.
R.C AshooriH.B Chan 《Solid State Communications》2003,127(2):79-88
We have developed a technique capable of measuring the tunneling current into both localized and conducting states in a 2D electron system (2DES). The method yields I-V characteristics for tunneling with no distortions arising from low 2D in-plane conductivity. We have used the technique to determine the pseudogap energy spectrum for electron tunneling into and out of a 2D system and, further, we have demonstrated that such tunneling measurements reveal spin relaxation times within the 2DEG. Pseudogap: In a 2DEG in perpendicular magnetic field, a pseudogap develops in the tunneling density of states at the Fermi energy. We resolve a linear energy dependence of this pseudogap at low excitations. The slopes of this linear gap are strongly field dependent. No existing theory predicts the observed behavior. Spin relaxation: We explore the characteristics of equilibrium tunneling of electrons from a 3D electrode into a high mobility 2DES. For most 2D Landau level filling factors, we find that electrons tunnel with a single, well-defined tunneling rate. However, for spin-polarized quantum Hall states (ν=1, 3 and 1/3) tunneling occurs at two distinct rates that differ by up to two orders of magnitude. The dependence of the two rates on temperature and tunnel barrier thickness suggests that slow in-plane spin relaxation creates a bottleneck for tunneling of electrons. 相似文献
17.
S. Bellucci P. Onorato 《The European Physical Journal B - Condensed Matter and Complex Systems》2010,73(2):215-221
Quantum interference effects in rings provide suitable means for
controlling spin at mesoscopic scales. Here we apply such a control
mechanism to the spin dependent transport in a one-dimensional
Aharonov-Bohm (AB) ring patterned in two-dimensional electron gases
(2DEGs) symmetrically coupled to two leads. We investigate the
ballistic conductance in the presence of an artificial crystal,
which is made up of 5 quantum dots. The study is essentially
based on the natural spinorbit interactions, due to the quantum
well potential that confines electrons in the 2DEG.
We focus on single-channel transport and solve for the spin
polarization of the current. As an important consequence of the
presence of spin splitting, we find the occurrence of spin
dependent current oscillations. The presence of lattice can be
useful to improve the spin filtering capability of the QR. In fact
modulating both the geometry of the dots and the strength of the
tunnel barriers between them it is now possible to obtain well
defined spin-dependent resonances allowing polarized transport.
The presence of isolated conductance peak
is useful in order to improve the efficiency of the spin filtering
also at non zero temperatures. 相似文献
18.
《Physica E: Low-dimensional Systems and Nanostructures》2010,42(10):1789-1794
We investigate the magnetocapacitance of the two-dimensional electron gas (2DEG) embedded in diluted magnetic semiconductors in the presence of Rashba spin–orbit interaction (SOI). We present calculations on the energy spectrum and density of states and show that the tunable spin–orbit coupling and the enhanced Zeeman splitting have a strong effect on the magnetocapacitance of the structure. In the presence of Rashba SOI, a typical beating pattern with well defined node-positions in the oscillating capacitance is observed. A simple relation that predicts the positions of nodes in the beating patterns is obtained. The interplay between the total Zeeman splitting (including the s–d exchange interaction) and the Rashba SOI is discussed. 相似文献
19.
F. Liang Y. H. Yang J. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(3):337-341
We propose an electrical scheme for the generation of a pure spin current without a charge current in a two-terminal device,
which
consists of a scattering region of a two-dimensional electron gas
(2DEG) with Rashba (R) and/or Dresselhaus (S) spin-orbit interaction (SOI)
and two normal leads. The SOI is modulated by a time-dependent gate
voltage to pump a spin current. Based on a tight-binding model and
the Keldysh Green’s function technique, we obtain the analytical
expression of the spin current. It is shown that a pure spin current
can be pumped out, and its magnitude could be modulated by
device parameters such as the oscillating frequency of the SOI, as
well as the SOI strength. Moreover, the spin polarisation direction of
the spin current could also be tuned by the strength ratio between
RSOI and DSOI. Our proposal provides not only a fully electrical means
to generate a pure spin current but also a way to control the spin
polarisation direction of the generated spin current. 相似文献
20.
We study the scattering of an electron of a 2DEG through a large point contact separating a region where the electrons are free and a region where the Rashba spin-orbit coupling is present. The scattering depends dramatically on the electron incidence angle showing double refraction within the Rashba region. For incidence not normal to the interface the electron spin state is not conserved. The calculated conductance exhibits an oscillating behavior as a function of spin state of the incident electrons with different spin down and spin up currents. Our model describes both a ferromagnetic semimetallic source and a simple metallic injection electrode. In the first case the electrons are injected in a pure spin state and in the second one they are unpolarized, that is in a statistical mixture of spin up and down states. In both the cases the passage through the large point contact produces spin polarized currents.Received: 30 July 2003, Published online: 23 December 2003PACS:
85.75.Hh Spin polarized field effect transistors - 72.25.-b Spin polarized transport - 73.23.Ad Ballistic transport 相似文献