Fizika Nizkikh Temperatur: Volume 43, Number 5 (May 2017), p. 772-781    ( to contents , go back )

Features of low-temperature tunneling magnetoresistance of pressed nanopowders of chromium dioxide CrO2

Yu.А. Kolesnichenko, N.V. Dalakova, Е.Yu. Beliayev, O.M. Bludov, V.А. Horielyi

B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine 47 Nauky Ave., Kharkiv 61103, Ukraine

О.М. Osmolowskaya, and М.G. Osmolowsky

Санкт-Петербургский государственный университет, химический факультет Санкт-Петербург, 198504, Россия

Received August 16, 2016

Abstract

Resistive and low-temperature magnetoresistive properties of pressed powders of ferromagnetic half-metal chromium dioxide (CrO2) with shape anisotropy of nanoparticles are studied. And we also studied the influence of Fe impurity on the value of tunneling resistance and magnetoresistance in CrO2 powders. It is found that the Fe impurity reduces resistance and tunneling magnetoresistance in chromium dioxide. We suggest that such a decrease of magnetoresistance in solid solution Cr1–xFexO2 is due to the formation of additional localized states at the iron impurities in a tunnel barrier. We found the influence of the speed of the magnetic field changing on the form of low-temperature tunneling magnetoresistance hysteretic loops in Cr1–xFexO2 powder. It is shown that the form of low-temperature magnetoresistance hysteresis depends on the relaxation rate of the magnetic moments of nanoparticles to an equilibrium state. The possible reasons for such dependence are discussed.

PACS: 75.47.–m Magnetotransport phenomena; materials for magnetotransport;
PACS: 75.47.Lx Magnetic oxides;
PACS: 75.50.Ss Magnetic recording materials;
PACS: 72.25.–b Spin polarized transport.

Key words: half metals, chromium dioxide, granular magnetic materials, tunnel magnetoresistance, blocked state.

Published online: March 24, 2017

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ISSN: 0132-6414 (Print) | ISSN: 1816-0328 (Online)