In-plane to perpendicular magnetic anisotropy switching in heavily-Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb with high Curie temperature

TL;DR

This study demonstrates the control of magnetic anisotropy in heavily-Fe-doped (Ga,Fe)Sb semiconductor films by varying thickness, showing a transition from in-plane to perpendicular anisotropy at room temperature, which is promising for spintronic devices.

Contribution

It reveals a thickness-dependent switching of magnetic anisotropy in (Ga,Fe)Sb with high Curie temperature, including a change from in-plane to perpendicular orientation and symmetry transformation.

Findings

Magnetic anisotropy switches from in-plane to perpendicular at ~42 nm thickness.

(Ga,Fe)Sb exhibits a two-fold in-plane symmetry and a four-fold out-of-plane symmetry.

The behavior differs from (Ga,Mn)As, highlighting unique anisotropy control in (Ga,Fe)Sb.

Abstract

We report switching of magnetic anisotropy (MA) from in-plane to perpendicular with increasing the thickness d of a (001)-oriented ferromagnetic-semiconductor (FMS) (Ga0.7,Fe0.3)Sb layer with a high Curie temperature (Tc > 320 K), using ferromagnetic resonance at room temperature. We show that the total MA energy (E) along the [001] direction changes its sign from positive (in-plane) to negative (perpendicular) with increasing d above an effective critical value \mathrm{d}_\mathrm{C}^\mathrm{*}\ ~ 42 nm. We reveal that (Ga,Fe)Sb has two-fold symmetry in the film plane. Meanwhile, in the plane perpendicular to the film including the in-plane [110] axis, the two-fold symmetry with the easy magnetization axis along [110] changes to four-fold symmetry with easy magnetization axis along <001> with increasing d. This peculiar behavior is different from that of (Ga,Mn)As, in which only the in-plane MA depends on the film thickness and has four-fold symmetry due to its dominant cubic anisotropy along the <100> axes. This work provides an important guide for controlling the easy magnetization axis of high-Tc FMS (Ga,Fe)Sb for room-temperature device applications.