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Andreev reflection through a quantum dot coupled with two ferromagnets and a superconductor

Yu Zhu·Qing-feng Sun·Tsung-han Lin
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Abstract

We study the Andreev reflection (AR) in a three terminal mesoscopic hybrid system, in which two ferromagnets (F$_1$ and F$_2$) are coupled to a superconductor (S) through a quantum dot (QD). By using non-equilibrium Green function, we derive a general current formula which allows arbitrary spin polarizations, magnetization orientations and bias voltages in F$_1$ and F$_2$. The formula is applied to study both zero bias conductance and finite bias current. The current conducted by crossed AR involving F$_1$, F$_2$ and S is particularly unusual, in which an electron with spin $σ$ incident from one of the ferromagnets picks up another electron with spin $\barσ$ from the other one, both enter S and form a Cooper pair. Several special cases are investigated to reveal the properties of AR in this system.

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Yu Zhu, Qing-feng Sun, Tsung-han Lin. 2001-04-06. Andreev reflection through a quantum dot coupled with two ferromagnets and a superconductor. https://doi.org/10.1103/physrevb.65.024516

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