Magnetocrystalline anisotropy-dependent six-fold symmetric anisotropic magnetoresistance in epitaxial Co_xFe_3−xO₄ films

Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Institute of Advanced Materials Physics, Faculty of Science, Tianjin University - Tianjin 300072, PRC

^(a) baihaili@tju.edu.cn

Received: 18 May 2012
Accepted: 9 October 2012

Abstract

The angular-dependent anisotropic magnetoresistance (AMR) of epitaxial Co_xFe_3−xO₄ films has been investigated systematically. The six-fold symmetric AMR was observed in the (111)-oriented epitaxial Co_xFe_3−xO₄ films in contrast to the four-fold symmetric AMR of the (100)- and (110)-oriented Co_xFe_3−xO₄ films. The six-fold term appears at temperatures below 200 K, and becomes more pronounced with increasing x, while no six-fold term was found in epitaxial Ni_xFe_3−xO₄ films. The six-fold characteristics observed in the epitaxial Co_xFe_3−xO₄ films are considered to be induced by the large magnetocrystalline anisotropy caused by Co addition, which directly proves that the AMR of magnetite is intimately related to magnetocrystalline anisotropy.