与铁磁引线耦合的垂直双量子点中的自旋极化输运

Spin-dependent transport in vertical double quantum dots coupled to ferromagnetic leads

研究与左右两个铁磁引线耦合的垂直双量子点系统中自旋极化流和自旋积累的性质。发现他们可以用外加偏压或两引线的磁化方向充分调节。在平行磁化方向时,电流的自旋极化率始终为正,并且敏感地依赖引线磁化率取值的相对大小。当磁化方向为反平行时,流的自旋极化率可正可负,在偏压等于正负库伦相互作用强度时分别出现谷和峰。自旋积累有相似的行为。尤其是在一个引线的磁化率为零时,会出现自旋二极管效应。

The properties of the current spin polarization and spin accumulation in vertical two quantum dots coupled to ferromagnetic leads are studied.It is found that they sensitively rely on the external applied bias voltage and the arrangement of the leads＇ magnetization directions.When the magnetizations are in parallel direction,the current spin polarization is always positive and depends on the relative magnitude of the two leads＇ magnetizations.However in the anti-parallel case,the current spin polarization can be positive or negative depending on the bias directions and has valley and peak when the bias voltage V=U.The spin accumulation has similar behaviors as that of the current spin polarization.Especially when the quantum dots are coupled to one ferromagnetic lead and one normal lead,the spin-diode effect will be observed.