Low Temperature Physics: 39, 211 (2013); https://doi.org/10.1063/1.4795172 (14 pages)
Физика Низких Температур: Том 39, Выпуск 3 (Март 2013), c. 276-292    ( к оглавлению , назад )

Point-contact Andreev-reflection spectroscopy of doped manganites: Charge carrier spin-polarization and proximity effects (Review Article)

V.N. Krivoruchko, A.I. D’yachenko, and V.Yu. Tarenkov

A.A. Galkin Donetsk Physics and Technology Institute National Academy of Sciences of the Ukraine 72 R. Luxemburg Str., Donetsk 83114, Ukraine
E-mail: krivoruc@gmail.com

Received September 18, 2012


Materials with spin-polarized charge carriers are the most demanded in the spin-electronics. Particularly requested are the so-called half-metals which have the maximum attainable value of carrier spin polarization. Doped manganites are in the list of compounds with, potentially, half-metallic properties. The point-contact (PC) Andreevreflection (AR) spectroscopy is a robust and direct method to measure the degree of current spin polarization. In this report, advances in PCAR spectroscopy of ferromagnetic manganites are reviewed. The experimental results obtained on “classic” s-wave superconductor — ferromagnetic manganites PCs, as well as related theoretical models applied to deduce the actual value of charge carrier spin-polarization, are discussed. Data obtained on “proximity affected” contacts is also outlined. Systematic and repeatable nature of a number of principal experimental facts detected in the AR spectrum of proximity affected contacts suggests that some new physical phenomena have been documented here. Different models of current flow through a superconductor–half-metal ferromagnet interface, as well as possibility of unconventional superconducting proximity effect, have been discussed.

PACS: 72.25.Mk Spin transport through interfaces;
PACS: 74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions;
PACS: 72.25.Ba Spin-polarized transport in metals.

Key words: current spin polarization, Andreev-reflection spectroscopy, ferromagnetic manganites, unconventional pairing.