FIG 4
![(color on line) A contour plot of the maximum P in [0, 2T] versus b and W , where E f = 5 meV, and the others are the same as those in Fig. 1.](profile/Gang_Su2/publication/242361935/figure/fig1/AS:669946791079939@1536739170113/color-on-line-A-contour-plot-of-the-maximum-P-in-0-2T-versus-b-and-W-where-E-f-5.png)
(color on line) A contour plot of the maximum P in [0, 2T] versus b and W , where E f = 5 meV, and the others are the same as those in Fig. 1.
Source publication
![FIG. 4: (color on line) A contour plot of the maximum P in [0, 2T]...](profile/Gang_Su2/publication/242361935/figure/fig1/AS:669946791079939@1536739170113/color-on-line-A-contour-plot-of-the-maximum-P-in-0-2T-versus-b-and-W-where-E-f-5_Q320.jpg)
Spin-polarized transport through a band-gap-matched ZnSe/Zn1-xMnxSe/ZnSe/Zn1-xMnxSe/ZnSe multilayer structure is investigated. The resonant transport is shown to occur at different energies for different spins owing to the split of spin subbands in the paramagnetic layers. It is found that the polarization of current density can be reversed in a ce...
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Citations
... Guo et al. [14][15][16][17][18] have demonstrated several effects in such DMS systems, such as, spin-dependent suppression and enhancement, the electric effect, spin splitting effect. Zhu et al. [19] investigated the size dependence of spin-polarized transport through ZnSe/Zn 1−x Mn x Se multi-layer structure and found that the polarization of current density can be reversed in a certain range of magnetic field. While most of the research in this field focus on the time-averaged quantities, relatively less to study the time-dependent properties, such as shot-noise. ...
We have investigated the photon-assisted shot noise properties in the magnetic field tunable heterostructures. Transport properties of the model structure are strongly dependent on the oscillatory field and the magnetic field. In this structure, electrons can absorb or emit one or multi-photons to reach the quasi-bound state. As a result, the transmission properties are affected considerably by photon-assisted tunneling and these features cause the nontrivial variations in the shot noise and Fano factor. It is found that the shot noise becomes spin-dependent and can be modulated not only by the magnetic field, but also by the oscillatory field. Both the spin-up and spin-down components of the shot noise can be greatly suppressed by the magnetic field, and can also be drastically enhanced by the harmonically driven field. Furthermore, with increasing external magnetic field, it is important to note that the enhanced intensity is decreased, even suppressed. These results suggest another method to suppress the shot noise via modulating the oscillatory field at a diluted-magnetic semiconductors/semiconductor structure.
... 1,2 II-VI semiconductor quantum structures based on ZnSe or CdTe, especially with diluted magnetic semiconductors (DMS), are of special interest because they enable us to optimize the transport properties by manipulating the external magnetic and electric fields. [3][4][5][6][7][8][9][10][11] In a Zn 1−x Mn x Se/ZnSe heterostructure with a single DMS layer, Egues 4 pointed out that increasing magnetic field leads to a strong suppression of the spin-up component of the current density, which were demonstrated by Slobodskyy et al. 6 Later, DMS heterostructures with the inclusion of the nonmagnetic barrier (NB, such as ZnBeSe, ZnMgSe, etc.) have also been investigated, both theoretically 12-17 and experimentally. [18][19][20][21][22][23][24] Based on the DMS/NB heterostructures, the concept of current and spin-filtering dual diodes were theoretically proposed by Zhai et al., 12 then Wójcik et al. numerically studied the intrinsic oscillations 16 and hysteresis loops 17 of spin-dependent electronic current. ...
We propose a spin selector based on periodic diluted-magnetic-semiconductor/nonmagnetic-barrier (DMS/NB) superlattices subjected to an external magnetic field. We find that the periodic DMS/NB superlattices can achieve 100% spin filtering over a dramatically broader range of incident energies than the diluted-magnetic-semiconductor/semiconductor (DMS/S) case studied previously. And the positions and widths of spin-filtering bands can be manipulated effectively by adjusting the geometric parameters of the system or the strength of external magnetic field. Such a compelling filtering feature stems from the introduction of nonmagnetic barrier and the spin-dependent giant Zeeman effect induced by the external magnetic field. We also find that the external electric field can exert a significant influence on the spin-polarized transport through the DMS/NB superlattices.
... We studied first a multi-layer structure, i.e. ZnSe/Zn 1−x -Mn x Se [46]. When there is no applied magnetic field, the Mn concentration in the paramagnetic layer is chosen so that the offsets of conduction and valence bands are rendered nearly zero, and the alternation of ZnSe and Zn 1−x Mn x Se may be used to build up spin superlattice. ...
... It is seen that the polarization can change its sign with increasing the magnitude of the magnetic field rather its direction. The thicknesses of the central ZnSe layer and the paramagnetic layer can affect the polarization dramatically since the thickness will determine the resonant condition [46]. ...
... E f = 5 meV is used for both. Thisfigure is taken from ref.[46]. ...
A brief review is presented, which includes the direct current, alternate current, electrical and thermoelectrical transport as well as spin transfer effect in a variety of spin-based nanostructures such as the magnetic tunnel junction (MTJ), ferromagnet(FM)-quantum dot (QD)/FM-FM, double barrier MTJ, FM-marginal Fermi liquid-FM, FM-unconventional superconductor-FM (FUSF), quantum ring and optical spin-field-effect transistor. The magnetoresistances in those structures, spin accumulation effect in FM-QD-FM and FUSF systems, spin injection and spin filter into semiconductor, spin transfer effect, photon-assisted spin transport, magnonassisted tunneling, electron-electron interaction effect on spin transport, laser-controlled spin dynamics, and thermoelectrical spin transport are discussed.
Using the Floquet theory and effective-mass approximation theory, we have investigated the terahertz (THz) photon-assisted transport through a magnetic-field tunable diluted magnetic semiconductor (DMS) structure with a nonmagnetic barrier under multi-physical fields, including an external magnetic field, an electric field and a THz field. It is found that a THz field and an electric field can greatly affect the transmission coefficient and current density as well as the corresponding polarizations. As a result, some asymmetric 'Fano' type transmission resonance appear at some specific energy. With the applied bias increasing, some quasi platforms of the polarization began to take shape. Furthermore, the transmission coefficient suppression or augmentation can be clearly seen from the variation tendency of current density. It is noteworthy that the amplitude of current-density polarization becomes larger under a THz field and a small magnetic field. These remarkable properties of spin polarization might be beneficial to the design of spin filtering devices.
Using the effective-mass approximation and Floquet theory, we theoretically investigate the terahertz photon-assisted transport through a ZnSe/Zn1−xMnxSeheterostructure under an external magnetic field, an electric field, and a spatially homogeneous oscillatory field. The results show that both amplitude and frequency of the oscillatory field can accurately manipulate the magnitude of the spin-dependent transmission probability and the positions of the Fano-type resonance due to photon absorption and emission processes. Transmission resonances can be enhanced to optimal resonances or drastically suppressed for spin-down electrons tunneling through the heterostructure and for spin-up ones tunneling through the same structure, resonances can also be enhanced or suppressed, but the intensity is less than the spin-down ones. Furthermore, it is important to note that transmission suppression can be clearly seen from both the spin-down component and the spin-up component of the current density at low magnetic field; at the larger magnetic field, however, the spin-down component is suppressed, and the spin-up component is enhanced. These interesting properties may provide an alternative method to develop multi-parameter modulation electron-polarized devices.
We investigate theoretically the effects of Dresselhaus spin-orbit coupling (DSOC) on the spin-dependent current and shot noise through II-VI diluted magnetic semiconductor/nonmagnetic semiconductor (DMS/NMS) barrier structures. The calculation of transmission probability is based on an effective mass quantum-mechanical approach in the presence of an external magnetic field applied along the growth direction of the junction and also applied voltage. We also study the dependence of spin-dependent properties on external magnetic field and relative angle between the magnetizations of two DMS layers in CdTe/CdMnTe heterostructures with including the DSOC effect. The results show that the DSOC has great different influence on transport properties of electrons with spin up and spin down in the considered system and this aspect may be utilized in designing new spintronics devices.
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.
Based on the transfer-matrix method and the group velocity concept, we investigate theoretically the spin tunneling time through single and double barriers of diluted magnetic semiconductor structures in the presence of the Rashba spin−orbit coupling (RSOC) effect. The calculation of transmission probability is based on an effective mass quantum-mechanical approach in the presence of an external magnetic field applied along the growth direction of the junction. The results show that the RSOC has great different influence on spin-dependent tunneling time of electrons with spin up and spin down in these structures. We also study the effect of zero-field conduction band offset on spin-dependent transmission properties. It is found that in the presence of RSOC and a positive zero-field conduction band offset as high as 10 meV, the results show a high degree of spin polarization and spin separation in the tunneling time in the considered system and this aspect may be utilized in designing new spin filter devices.
The present research is devoted to the investigation of electron spin transmission through a nanoelectronic device. This device is modeled as nonmagnetic semiconductor quantum dot coupled to two diluted magnetic semiconductor leads. The spin transport characteristics through such a device are investigated under the effect of an ac-field of a wide range of frequencies. The present result shows a periodic oscillation of the conductance for both the cases of parallel and antiparallel spin alignment. These oscillations are due to Fano-resonance. Results for spin polarization and giant magneto-resistance show the coherency property. The present research might be useful for developing single spin-based quantum bits (qubits) required for quantum information processing and quantum spin-telecommunication.
We investigate theoretically the effects of Rashba spin–orbit coupling on the spin dependent transport through diluted magnetic semiconductor single and double barrier structures in the presence of a magnetic field. We find that the Rashba spin–orbit coupling gives rise to an enhancement of the negative tunnelling magnetoresistance of the diluted magnetic semiconductor single barrier structure and a pronounced beating pattern in the tunnelling magnetoresistance and spin polarization of the diluted magnetic semiconductor double barrier structure.
