Volume 75, Number 2, July 2006
|Page(s)||294 - 300|
|Section||Condensed matter: electronic structure, electrical, magnetic, and optical properties|
|Published online||23 June 2006|
Subgap magnetotransport in point contacts
Donetsk Physics & Technology Institute NAS of Ukraine Str. R. Luxemburg 72, 83114 Donetsk, Ukraine
Accepted: 31 May 2006
Andreev reflection spectroscopy has been used to probe mutual influence of superconductivity and ferromagnetism in contacts of a low-temperature superconductor (S), Pb, and a half-metallic ferromagnet, La0.65Ca0.35 MnO3 (LCMO). In the contacts, which we distinguish as proximity-affected ones, a few unusual effects have been detected: i) a spectacular drop in the resistance of the contacts at the onset of the Pb superconductivity; ii) excess current and doubling of the normal-state conductance; iii) subharmonic gap structure; and iv) the ratio of the single-particle gap to the Pb superconducting transition temperature is anomalously large. Microscopically, our results can most reasonably be explained assuming a conversion from spin singlet pairs to spin triplets at the S/LCMO interface and a long-range proximity effect.
PACS: 74.45.+c – Proximity effects; Andreev effect; SN and SNS junctions / 74.78.Fk – Multilayers, superlattices, heterostructures / 74.50.+r – Tunneling phenomena; point contacts, weak links, Josephson effects
© EDP Sciences, 2006
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