Uniaxial magnetic anisotropy induced low field anomalous anisotropic magnetoresistance in manganite thin films

Zhaoliang Liao,Gertjan Koster,Guus Rijnders,Mark Huijben

doi:10.1063/1.4895956

Abstract

La2/3Sr1/3MnO3 films with uniaxial magnetic anisotropy were coherently grown on NdGaO3 (110) substrates. The uniaxial anisotropy has strong effect on magnetoresistance (MR). A positive MR was observed when the current is along magnetic easy axis under the current-field perpendicular geometry. In contrast, no positive MR is observed when current is along the magnetic hard axis regardless of the field direction. Our analysis indicates that the anomalous anisotropic MR effect arises from the uniaxial magnetic anisotropy caused stripe domains which contribute to strong anisotropic domain wall resistivity.

Highlights

Domain walls separating uniform magnetic domains of different orientations play a central role in magnetic materials and have, attracted broad experimental and theoretical interest.[1,2,3,4,5,6,7,8,9] The appearance of these domain walls affects the magnetic behavior and contributes to the electrical magnetoresistance (MR) due to the domain wall resistivity (DWR).[1]
Positive DWR behavior was explained by the reflection of electrons from domain wall,[9] mixed spin channel conduction,[8] and Hall effect,[14] while a negative DWR behavior could be caused by the destruction of weak localization at domain walls.[15]
Introducing anisotropic strain to the ferromagnetic LSMO thin films on (110) NdGaO3 (NGO) substrates leads to uniaxial magnetic anisotropy (MA),[21] which will result in a periodic stripe domain structure.[22]

Summary

Introduction

Domain walls separating uniform magnetic domains of different orientations play a central role in magnetic materials and have, attracted broad experimental and theoretical interest.[1,2,3,4,5,6,7,8,9] The appearance of these domain walls affects the magnetic behavior and contributes to the electrical magnetoresistance (MR) due to the domain wall resistivity (DWR).[1]. Ferromagnetic LSMO exhibits a very high Curie temperature of 370 K16 with almost 100% spin polarization[17] and is emerging as a very promising material for various applications such as memory devices.[18,19,20] Introducing anisotropic strain to the ferromagnetic LSMO thin films on (110) NdGaO3 (NGO) substrates leads to uniaxial magnetic anisotropy (MA),[21] which will result in a periodic stripe domain structure.[22] This highly anisotropic domain pattern consisting of a high ratio of domain wall to domain is ideal for investigating the electrical behavior parallel and perpendicular to the domain walls.[1] Variations in the magnetoresistance caused by the change of the density and orientation of domain walls with magnetic field can reflect the domain wall resistivity and underlying coupling between electron and spin within the domain walls.

Results

Conclusion