Superconducting spin filter

N. M. Chtchelkatchev

doi:10.1134/1.1622037

paper

Superconducting spin filter

arXiv:cond-mat/0306552 · doi:10.1134/1.1622037

Abstract

Consider two normal leads coupled to a superconductor; the first lead is biased while the second one and the superconductor are grounded. In general, a finite current $I_{2} (V_{1}, 0)$ is induced in the grounded lead 2; its magnitude depends on the competition between processes of Andreev and normal quasiparticle transmission from the lead 1 to the lead 2. It is known that in the tunneling limit, when normal leads are weakly coupled to the superconductor, $I_{2} (V_{1}, 0) = 0$ , if $∣ V_{1} ∣ < Δ$ and the system is in the clean limit. In other words, Andreev and normal tunneling processes compensate each-other. We consider the general case: the voltages are below the gap, the system is either dirty or clean. It is shown that $I_{2} (V_{1}, 0) = 0$ for general configuration of the normal leads; if the first lead injects spin polarized current then $I_{2} = 0$ , but spin current in the lead-2 is finite. XISIN structure, where X is a source of the spin polarized current could be applied as a filter separating spin current from charge current. We do an analytical progress calculating $I_{1} (V_{1}, V_{2}), I_{2} (V_{1}, V_{2})$ .

5 pages, references added

Superconducting spin filter

Abstract

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