Interfacial orbital preferential occupation induced controllable uniaxial magnetic anisotropy observed in Ni/NiO(110) heterostructures

Yuan-Hua Lin,Yu-Jun Zhang,Ce-Wen Nan,Ji Ma,Nian-Xiang Sun,Liang Wu,Qing-Hua Zhang,Atsushi Fujimori,Jing Ma

doi:10.1038/s41535-017-0020-0

Abstract

Unexpected physical phenomena could emerge at heterostructure interfaces, and interface effects are also capable of giving rise to magnetic anisotropy. In this work, a peculiar uniaxial magnetic anisotropy in (polycrystalline Ni)/(epitaxial NiO)/SrTiO3(110) heterostructures is investigated. Thickness dependence of the anisotropy confirms its interfacial effect nature. The NiO antiferromagnetic ordering induced interface exchange coupling should not be responsible for the anisotropy according to the temperature dependence. Our soft X-ray linear dichroism and magnetic circular dichroism results show a preferential occupation of orbital parallel to in-plane [100] at Ni/NiO interface and the origin of this uniaxial anisotropy is closely related to the occupation of Ni 3d orbitals at the interface. The magnetocrystalline anisotropy and piezoelectric strain could be utilized to manipulate this uniaxial anisotropy and realize controllable in-plane easy axis switching, which could be promising in future application of spintronics devices.

Highlights

Involving four performers named charge, spin, lattice, and orbital, heterostructure interfaces provide a charming stage for them to interact
Interface engineering has already become a tantalizing subject, by working on which we can obtain abundant knowledge of basic physics concealed in heterostructure interfaces and develop new ideas for designing devices based on interface effects, which are applicable in future spintronics
In exchange biased AFM/FM systems, magnetic anisotropy of ferromagnetic layer is controlled by anisotropy of AFMs through interface exchange coupling

Summary

Introduction

Involving four performers named charge, spin, lattice, and orbital, heterostructure interfaces provide a charming stage for them to interact. Interface effect induced magnetic anisotropy has been a permanently attractive topic for researchers. Interface spin exchange interaction[5, 6, 22,23,24] has become the first considered mechanism for interface magnetic anisotropy, which links the anisotropy of adjacent magnetically ordered components. In exchange biased AFM/FM systems, magnetic anisotropy of ferromagnetic layer is controlled by anisotropy of AFMs through interface exchange coupling. Interfacial charge effect[25] has been proposed as an origin of magnetic anisotropy in (Ga,Mn)

Methods

Results

Conclusion