自旋翻转系数对量子点系统热电的影响
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摘要
基于电子共隧穿分析点内自旋翻转和电极内翻转效应对量子器件热电特性的影响,进而寻找系统内热电输运的最佳条件。电导光谱的位置只决定于自旋翻转系数±η,随着自旋翻转系数的增加,两个峰的位置逐渐地向两边移动。电子通道的宽度随着电极的极化强度、无量纲比值和铁磁电极磁化的改变而改变,电导谱的幅值取决于极化强度、无量纲比值和铁磁电极磁化的夹角θ。随着铁磁电极的磁化夹角θ逐渐增加,在spin-majority电子通道中的电导光谱逐渐增加,而spin-minority电子通道中电导光谱逐渐的减小。在无量纲常数α极小值范围内可以等到最佳的热电效应。
Based on electron cotunneling, we will research the thermoelectric transport of quantum devices by effects of the spinflip coefficient and magnetization, and then obtain the optimum condition. The position of conductance spectrum gradually move toward both sides with increasing the spin-flip coefficient. Because the position of conductance depends on the spin-flip coefficient. The width of the electron channel varies with the polarization dimensionless ratio and magnetization. So the conductance spectrum varies with these parameters. the conductance in the spin-majority electron channels gradually increases and the conductance in the spin-minority electron channels gradually decreases, when the magnetization angle increases, the optimal thermoelectric effect can be obtained in the minimum range of the dimensionless constant.
Based on electron cotunneling, we will research the thermoelectric transport of quantum devices by effects of the spinflip coefficient and magnetization, and then obtain the optimum condition. The position of conductance spectrum gradually move toward both sides with increasing the spin-flip coefficient. Because the position of conductance depends on the spin-flip coefficient. The width of the electron channel varies with the polarization dimensionless ratio and magnetization. So the conductance spectrum varies with these parameters. the conductance in the spin-majority electron channels gradually increases and the conductance in the spin-minority electron channels gradually decreases, when the magnetization angle increases, the optimal thermoelectric effect can be obtained in the minimum range of the dimensionless constant.
引文
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[2]Hanson R,Awschalom D D.Coherent manipulation of single spins in semiconductors[J].Nature,2008,453:1043.
[3]Fujisawa T,Austing D G,Tokura Y,et al.Allowed and forbidden transitions in artificial hydrogen and helium atoms[J].Nature,2002,419:278-281.
[4]Silva G G,Aacute O,Guevara M L L,et al.Enhancement of thermoelectric efficiency and violation of the Wiedemann-Franz law due to Fano effect[J].J Appl Phys,2012,111:053704.
[5]Gordon D G,Shtrikman H,Mahalu D,et al.Kondo Effect in a Single-Electron Transistor[J].Nature,1998,391:156.
[6]Kobayashi K,Aikawa H,Katsumoto S,et al.Tunning of the Fano effect through a quantum dot in an Aharonov-Bohm interferometer[J].Phys Rev Lett,2002,88:256806.
[7]Wirkowicz R,Weirzbicki M,Barnas J.Thermoelectric effects in transport through quantum dots attached to ferromagnetic leads with noncollinear magnetic moments[J].Phys Rev B,2009,80:195409.
[8]Wirkowicz R,Weirzbicki M,Barnas J.Electric and thermoelectric phenomena in a multilevel quantum dot attached to ferromagnetic electrodes[J].Phys Rev B,2010,82:165334.(下转第26页)(13)
[9]Haug H,Jauho A P.Quantum Kinetics in Transport and Optics of Semiconduct-ors[M].Springer-Verlag Berlin,2008.
[10]Svensson S F,Persson A I,Hoffmann E A,et al.Lineshape of the thermopower of quantum dots[J].New J Phys,2012,14:033041.
[11]Wang B,Wang J,Guo H.Nonlinear Spin Polarized Transport through a Ferromagnetic Nonmagnetic Ferromagnetic Junction[J].Journal of the physical of japan,2001,70:2615-2651.
[12]Miaiorny M,Barna J.Spin-dependent thermoelectric effects in transport through a nanoscopic junction involving a spin impurity[J].Phys Rev B,2014,89:235438.
[13]Saito K,Benenti G,Casati G,et al.Thermopower with broken time reve-rsal symmetry[J].Phys Rev B,2011,84:201306(R).
[14]Brandner K,Saito K,Seifert U.Strong Bounds on Onsager Coefficients and Efficienty for Threen-Terminal Thermoelectric Transport in a Magnetic Field[J].Phys Rev Lett,2013,110:070603.
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