Spin-flip scattering in time-dependent transport through a quantum dot: Enhanced spin-current and inverse tunneling magnetoresistance

Article

关键词: ELECTRON-SPIN;    POLARIZATION;    MEMORY;   

DOI  :  10.1103/PhysRevB.78.155301

来源: SCIE

【 摘 要 】

We study the effects of spin-flip scatterings on the time-dependent transport properties through a magnetic quantum dot attached to normal and ferromagnetic leads. The transient spin dynamics as well as the steady-state tunneling magnetoresistance (TMR) of the system are investigated. The absence of a definite spin-quantization axis requires the time propagation of two-component spinors. We present numerical results in which the electrodes are treated both as one-dimensional tight-binding wires and in the wide-band limit approximation. In the latter case we derive a transparent analytic formula for the spin-resolved current, and transient oscillations damped over different time scales are identified. We also show that in the presence of spin-flip scatterings the TMR can be inverted even for symmetrically coupled leads. For any given strength of the spin-flip coupling the TMR becomes negative provided the ferromagnetic polarization is larger than some critical value. Finally we show how the full knowledge of the transient response allows for enhancing the spin current by properly tuning the period of a pulsed bias.

【 授权许可】

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