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MA: Fachverband Magnetismus

MA 17: Poster Session I

MA 17.90: Poster

Dienstag, 8. März 2016, 09:30–12:30, Poster B1

Twofold and fourfold symmetric anisotropic magnetoresistance effect in a model with crystal field — •Satoshi Kokado¹ and Masakiyo Tsunoda² — ¹Shizuoka University, Hamamatsu, Japan — ²Tohoku University, Sendai, Japan

We theoretically study the twofold and fourfold symmetric anisotropic magnetoresistance (AMR) effect [1]. We first extend our previous model [2,3] to a model including the crystal field effect [1]. Using the model, we next obtain an analytical expression of the AMR ratio, i.e., AMR(φ)=C₀ + C₂ cos(2 φ) + C₄ cos(4 φ), with C₀=C₂ − C₄ [1]. Here, φ is the relative angle between the magnetization direction and the electric current direction and C₂ (C₄) is a coefficient of the twofold (fourfold) symmetric term. The coefficients C₂ and C₄ are expressed by a spin-orbit coupling constant, an exchange field, a crystal field, and s-s and s-d scattering resistivities. Using this expression, we analyze the experimental results for Fe₄N [4,5], in which |C₂| and |C₄| increase with decreasing temperature. The experimental results can be reproduced by assuming that the tetragonal distortion increases with decreasing temperature.

[1] S. Kokado et al., J. Phys. Soc. Jpn. 84, 094710 (2015).
[2] S. Kokado et al., J. Phys. Soc. Jpn. 81, 024705 (2012).
[3] S. Kokado et al., Adv. Mater. Res. 750-752, 978 (2013).
[4] M. Tsunoda et al., Appl. Phys. Express 3, 113003 (2010).
[5] K. Kabara et al., Appl. Phys. Express 7, 063003 (2014).