共查询到20条相似文献,搜索用时 31 毫秒
1.
Xing-Tao An 《Physics letters. A》2008,372(8):1313-1318
Based on the scattering approach, we investigate transport properties of electrons in a one-dimensional waveguide that contains a ferromagnetic/semiconductor/ferromagnetic heterojunction and tunnel barriers in the presence of Rashba and Dresselhaus spin-orbit interactions. We simultaneously consider significant quantum size effects, quantum coherence, Rashba and Dresselhaus spin-orbit interactions and noncollinear magnetizations. It is found that the tunnel barrier plays a decisive role in the transmission coefficient and shot noise of the ballistic spin electron transport through the heterojunction. When the small tunnel barriers are considered, the transport properties of electrons are quite different from those without tunnel barriers. 相似文献
2.
Spin-dependent electron transport of a waveguide with Rashba spin--orbit coupling in an electromagnetic field 下载免费PDF全文
We investigate theoretically the spin-dependent electron
transport in a straight waveguide with Rashba spin--orbit coupling
(SOC) under the irradiation of a transversely polarized
electromagnetic (EM) field. Spin-dependent electron conductance and
spin polarization are calculated as functions of the emitting
energy of electrons or the strength of the EM field by adopting the mode
matching approach. It is shown that the spin polarization can be
manipulated by external parameters when the strength of Rashba
SOC is strong. Furthermore, a sharp step structure is found to exist
in the total electron conductance. These results can be understood
by the nontrivial Rashba subbands intermixing and the electron
intersubband transition when a finite-range transversely polarized
EM field irradiates a straight waveguide. 相似文献
3.
P. Liu S.-J. Xiong 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(4):513-516
The spin Hall transport properties in a two-dimensional electron
system with both Rashba spin-orbit coupling (SOC) and magnetic
impurities are investigated. Electrons are scattered by impurities
through an exchange interaction that leads to spin flip-flop
processes and so changes the spin Hall effect induced by the SOC.
The spin Hall conductance is calculated in a 4-terminal system
using the Landauer-Buttiker formula and Green function approach.
In comparison with the simulation results on nonmagnetic
impurities doping systems, our results reveal that the spin Hall
conductance is still nonzero in a system with a large density of
magnetic impurities and a finite intensity of the exchange
interaction between the electrons and impurities, and its sign may
be altered when the doping density and interaction strength are
large enough. 相似文献
4.
Based on the transfer-matrix method, the spin transport properties through a graphene-based multi-barrier nanostructure with an exchange field and Rashba spin orbit coupling (SOC), have been investigated. It is found that if Rashba SOC equals to the exchange field, the multi-barrier nanostructure is an efficient way to achieve spin rotators and spin filters. In addition, it is also found that the shot noise of a spin state can be enhanced by electrostatic potential, and plateaus of the Fano factor is formed. 相似文献
5.
We investigate the ballistic transport properties of an electron traversing through a two-dimensional electron gas with the Rashba and Dresselhaus spin–orbit coupling (R–D SOC) coexistent. A nonzero incident angle is considered. The relation between the transmission and the incident angle, the interfacial scattering strength, the length of the SOC region and the SOC intensity are revealed. The transmission strength decays when the incident angle is larger than a critical angle. The transport spin polarization is remarkably modulated by the coaction of the two types of SOC. 相似文献
6.
Z.-Y. Zhang 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(1):65-69
Along the lines of Blonder, Tinkham and Klapwijk, we investigate
the charge transport through ferromagnet/two-dimensional
electronic gas/d-wave superconductor (F/2DEG/S) junctions in the
presence of Rashba spin-orbit (SO) coupling and focus our
attention on the interplay between spin polarization and spin
precession. At zero spin polarization, the spin-mixing scattering
resulted from Rashba SO coupling decreases the zero-bias
conductance peak. Under spin polarization, spin precession
introduces novel Andreev reflection, which competes with the
effect of spin-mixing scattering. If the F layer is a half metal,
the later effect is overwhelmed by that of novel Andreev
reflection. As a result, the zero-bias conductance dip caused by
spin polarization is enhanced, and at strong Rashba SO coupling, a
split zero-bias peak is found in the gap. In an intermediate
region where the two effects are comparable with each other, the
zero-bias conductance shows a reentrant behavior as a function of
Rashba SO coupling. 相似文献
7.
Transport polygonal properties in a multi-terminal regular quantum ring with Rashba spin-orbit coupling 下载免费PDF全文
<正>Transport properties in a multi-terminal regular polygonal quantum ring with Rashba spin-orbit coupling(SOC) are investigated analytically using quantum networks and the transport matrix method.The results show that conductances remain at exactly the same values when the output leads are located at axisymmetric positions.However,for the nonaxisymmetrical case,there is a phase difference between the upper and lower arm,which leads to zero conductances appearing periodically.An isotropy of the conductance is destroyed by the Rashba SOC effect in the axisymmetric case. In addition,the position of zero conductance is regulated with the strength of the Rashba SOC. 相似文献
8.
The effect of Rashba spin-orbit coupling (SOC) on electron transport in asymmetrically coupled regular polygonal quantum ring is investigated. In absence of SOC, two kinds of conductance zeros appear periodically. In presence of SOC, one kind of conductance zero can be lifted by the Rashba SOC, the others persist. 相似文献
9.
Considering the Rashba spin-orbit interaction in the semiconductor, we study theoretically the spin-polarized transport in a two-dimensional ferromagnetic semiconductor double tunnel junctions by a quantum-mechanical approach. It is found that the transmission coefficient shows typical resonant transmission properties and the Rashba spin-orbit coupling has great different influences on the transmission coefficients of electrons with spin-up and down and tunnelling magnetoresistance (TMR). More importantly, the TMR is significantly enhanced by increasing the spin-orbit coupling, which is very useful for the designing of magnetic digital and memory sensor. 相似文献
10.
We investigate spin-dependent current and shot noise, taking into account the Rashba spin–orbit coupling (RSOC) effect in double diluted magnetic semiconductor (DMS) barrier resonant tunneling diodes. The calculation is based on an effective mass approach. The magnetization of DMS is calculated by the mean-field approximation in low magnetic field. The spin-splitting of DMS depends on the sp–d exchange interaction. We also examine the dependence of transport properties of CdTe/CdMnTe heterostructures on applied voltage and relative angle between the magnetization of two DMS layers. It is found that the RSOC has great different influence on the transport properties of tunneling electrons with spin-up and spin-down, which have different contributions to the current and the shot noise. Also, we can see that the RSOC enhances the spin polarization of the system, which makes the nanostructure a good candidate for new spin filter devices. Thus, these numerical results may shed light on the next applications of quantum multilayer systems and make them a good choice for future spintronics devices. 相似文献
11.
C. Bai Y. -L. Yang X. -D. Zhang 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(1):79-84
Based on the extended Blonder-Tinkham-Klapwijk (BTK) approach, we have investigated the coherent quantum transport in two-dimensional
electron gas/superconductor (2DEG/SC) double tunneling junctions in the presence of the Rashba spin-orbit coupling (RSOC).
It is found that all the reflection coefficients in BTK theory as well as conductance spectra oscillate with the external
voltage and energy. The oscillation feature of conductance can be tuned largely by the RSOC for low insulating barriers, while
for high insulating barriers it is almost independent of the RSOC. These phenomena are essentially different from those found
in ferromagnet/superconductor double tunneling junctions. 相似文献
12.
Charge Transport Properties of the Majorana Zero Mode Induced Noncollinear Spin Selective Andreev Reflection 下载免费PDF全文
We study the charge transport properties of the spin-selective Andreev reflection(SSAR)effect between a spin polarized scanning tunneling microscope(STM)tip and a Majorana zero mode(MZM).Considering both the MZM and the excited states,we calculate the conductance and the shot noise power of the noncollinear SSAR using scattering theory.We find that the excited states give rise to inside peaks.Moreover,we numerically calculate the shot noise power and the Fano factor of the SSAR effect.Our calculation shows that the shot noise power and the Fano factor are related to the angle between the spin polarization direction of the STM tip and that of the MZM,which provide additional characteristics to detect the MZM via SSAR. 相似文献
13.
We study the full counting statistics of transport electrons through a semiconductor two-level quantum dot with Rashba spin–orbit (SO) coupling, which acts as a nonabelian gauge field and thus induces the electron transition between two levels along with the spin flip. By means of the quantum master equation approach, shot noise and skewness are obtained at finite temperature with two-body Coulomb interaction. We particularly demonstrate the crucial effect of SO coupling on the super-Poissonian fluctuation of transport electrons, in terms of which the SO coupling can be probed by the zero-frequency cumulants. While the charge currents are not sensitive to the SO coupling. 相似文献
14.
We study the conductance through a ring described by the Hubbard model (such as an array of quantum dots), threaded by a magnetic flux and subject to Rashba spin-orbit coupling (SOC). We develop a formalism that is able to describe the interference effects as well as the Kondo effect when the number of electrons in the ring is odd. In the Kondo regime, the SOC reduces the conductance from the unitary limit, and, in combination with the magnetic flux, the device acts as a spin polarizer. 相似文献
15.
Spin transport properties in ferromagnet/superconductor junctions on topological insulator 下载免费PDF全文
The spin-dependent Andreev reflection is investigated theoretically by analyzing the electronic transport in a thin-film topological insulator (TI) ferromagnet/superconductor (FM/SC) junction. The tunneling conductance and shot noise are calculated based on the Dirac-Bogoliubov-de Gennes equation and Blonder-Tinkham-Klapwijk theory. It is found that the magnetic gap in ferromagnet can enhance the Andreev retro-reflection but suppress the specular Andreev reflection. The gate potential applied to the electrode on top of superconductor can enhance the two types of reflections. There is a transition between the two types of reflections at which both the tunneling conductance and differential shot noise become zero. These results provide a method to realize and detect experimentally the intra-band specular Andreev reflection in thin film TI-based FM/SC structures. 相似文献
16.
Using a transfer matrix method, we investigate spin transport through a chain of polygonal rings with Dresselhaus spin-orbit coupling(DSOC). The spin conductance is dependent on the number of sides in the polygons. When DSOC is considered in a chain which also has Rashba spin-orbit coupling(RSOC) of the same magnitude, the total conductance is the same as that for the same chain with no SOC. However, when the two types of SOC have different values, there results a unique anisotropic conductance. 相似文献
17.
Electron transport properties of an ideal one-dimensional (1D) quantum wire are studied including spatially periodic Rashba spin–orbit coupling (SOC) and Dresselhaus SOC. By comparing with the previous work [S.J. Gong, Z.Q. Yang, J. Phys. Condens. Matter 19 (2007) 446209], two transmission gaps appear in the transmission probability of electrons and their widths are also broadened dramatically. Moreover, it is found that their widths are sensitive not only to the strength of SOCs but also to the length ratio of SOCs segment and non-SOCs segment. In addition, a ‘circle-type’ transmission behavior has been found by tuning the strength of SOCs continuously. Our results may extend the previous work and provide an more effective method to manipulate the current in nanoelectric devices. 相似文献
18.
Wu F Queipo P Nasibulin A Tsuneta T Wang TH Kauppinen E Hakonen PJ 《Physical review letters》2007,99(15):156803
We have measured shot noise in single-walled carbon nanotubes with good contacts at 4.2 K at low frequencies (f=600-850 MHz). We find a strong modulation of shot noise over the Fabry-Perot pattern; in terms of the differential Fano factor the variation ranges over 0.4-1.2. The shot noise variation, in combination with differential conductance, is analyzed using two (spin-degenerate) modes with different, energy-dependent transmission coefficients. Deviations from the predictions from Landauer-Buttiker formalism are assigned to electron-electron interactions. 相似文献
19.
Qiao Chen 《Physics letters. A》2008,372(15):2714-2719
We have investigated the spectral density of shot noise of the system with a quantum dot (QD) coupled to two single-wall carbon nanotube terminals, where a rotating magnetic field is applied to the QD. The carbon nanotube (CN) terminals act as quantum wires which open quantum channels for electrons to transport through. The shot noise and differential shot noise exhibit novel behaviors originated from the quantum nature of CNs. The shot noise is sensitively dependent on the rotating magnetic field, and the differential shot noise exhibits asymmetric behavior versus source-drain bias and gate voltage. The Fano factor of the system exhibits the deviation of shot noise from the Schottky formula. The super-Poissonian and sub-Poissonian shot noise can be achieved in different regime of source-drain bias. 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