Observation of uniaxial anisotropy along the [100] direction in crystalline Fe film.

Seul-Ki Bac,Taehee Yoo,Sanghoon Lee,Hakjoon Lee,X Liu,J K Furdyna,Seonghoon Choi,Sangyoep Lee

doi:10.1038/srep17761

Abstract

We report an observation of uniaxial magnetic anisotropy along the [100] crystallographic direction in crystalline Fe film grown on Ge buffers deposited on a (001) GaAs substrate. As expected, planar Hall resistance (PHR) measurements reveal the presence of four in-plane magnetic easy axes, indicating the dominance of the cubic anisotropy in the film. However, systematic mapping of the PHR hysteresis loops observed during magnetization reversal at different field orientations shows that the easy axes along the and are not equivalent. Such breaking of the cubic symmetry can only be ascribed to the presence of uniaxial anisotropy along the direction of the Fe film. Analysis of the PHR data measured as a function of orientation of the applied magnetic field allowed us to quantify the magnitude of this uniaxial anisotropy field as Oe. Although this value is only 1.5% of cubic anisotropy field, its presence significantly changes the process of magnetization reversal, revealing the important role of the uniaxial anisotropy in Fe films. Breaking of the cubic symmetry in the Fe film deposited on a Ge buffer is surprising, and we discuss possible reason for this unexpected behavior.

Highlights

Measurements even very small contributions of a uniaxial anisotropy to the reorientation of magnetization between magnetic easy axes lead to conspicuous asymmetric behavior of the hysteresis loops observed by planar Hall resistance (PHR), as discussed below
The “jumps” in the value of PHR seen in Fig. 2 occur at fields at which the magnetization switches from one in-plane easy axis to another during the field sweep28,29
We have investigated the magnetic anisotropy of the Fe film grown on GaAs substrate and the Ge buffer layer

Summary

Introduction

Measurements even very small contributions of a uniaxial anisotropy to the reorientation of magnetization between magnetic easy axes lead to conspicuous asymmetric behavior of the hysteresis loops observed by planar Hall resistance (PHR), as discussed below. The “jumps” in the value of PHR seen in Fig. 2 occur at fields at which the magnetization switches from one in-plane easy axis to another during the field sweep28,29.

Results

Conclusion