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arXiv · 1202.5219

Impurity-assisted Andreev reflection at a spin-active half-metal-superconductor interface

Francis B. Wilken·Piet W. Brouwer
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Abstract

The Andreev reflection amplitude at a clean interface between a half-metallic ferromagnet (H) and a superconductor (S) for which the half metal's magnetization has a gradient perpendicular to the interface is proportional to the excitation energy $\varepsilon$ and vanishes at $\varepsilon=0$ [B\'{e}ri {\em et al.}, Phys.\ Rev.\ B {\bf 79}, 024517 (2009)]. Here we show that the presence of impurities at or in the immediate vicinity of the HS interface leads to a finite Andreev reflection amplitude at $\varepsilon=0$. This impurity-assisted Andreev reflection dominates the low-bias conductance of a HS junction and the Josephson current of an SHS junction in the long-junction limit.

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Francis B. Wilken, Piet W. Brouwer. 2012-02-23. Impurity-assisted Andreev reflection at a spin-active half-metal-superconductor interface. https://doi.org/10.1103/physrevb.85.134531

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