Hidden peculiar magnetic anisotropy at the interface in a ferromagnetic perovskite-oxide heterostructure

TL;DR

This study uncovers a unique interfacial magnetic anisotropy in a ferromagnetic oxide heterostructure, revealing energy-dependent behavior and potential for magnetic property control via band structure engineering.

Contribution

It demonstrates the detection of a peculiar interfacial magnetic anisotropy using tunneling magnetoresistance, highlighting a novel energy-dependent magnetic behavior at the interface.

Findings

Discovery of strong two-fold magnetic anisotropy at the interface

Observation of 90° rotation of easy magnetization axis at 0.2 eV below Fermi level

Linking the anisotropy behavior to band transitions between eg and t2g

Abstract

Understanding and controlling the interfacial magnetic properties of ferromagnetic thin films are crucial for spintronic device applications. However, using conventional magnetometry, it is difficult to detect them separately from the bulk properties. Here, by utilizing tunneling anisotropic magnetoresistance in a single-barrier heterostructure composed of La0.6Sr0.4MnO3 (LSMO)/ LaAlO3 (LAO)/ Nb-doped SrTiO3 (001), we reveal the presence of a peculiar strong two-fold magnetic anisotropy (MA) along the [110]c direction at the LSMO/LAO interface, which is not observed in bulk LSMO. This MA shows unknown behavior that the easy magnetization axis rotates by 90{\deg} at an energy of 0.2 eV below the Fermi level in LSMO. We attribute this phenomenon to the transition between the eg and t2g bands at the LSMO interface. Our finding and approach to understanding the energy dependence of the MA demonstrate a new possibility of efficient control of the interfacial magnetic properties by controlling the band structures of oxide heterostructures.