Fermi level shifting, charge transfer and induced magnetic coupling at La0.7Ca0.3MnO3/LaNiO3 interface.

Xingkun Ning,Zhidong Zhang,Zhanjie Wang

doi:10.1038/srep08460

Abstract

A large magnetic coupling has been observed at the La0.7Ca0.3MnO3/LaNiO3 (LCMO/LNO) interface. The x-ray photoelectron spectroscopy (XPS) study results show that Fermi level continuously shifted across the LCMO/LNO interface in the interface region. In addition, the charge transfer between Mn and Ni ions of the type Mn3+ − Ni3+ → Mn4+ − Ni2+ with the oxygen vacancies are observed in the interface region. The intrinsic interfacial charge transfer can give rise to itinerant electrons, which results in a “shoulder feature” observed at the low binding energy in the Mn 2p core level spectra. Meanwhile, the orbital reconstruction can be mapped according to the Fermi level position and the charge transfer mode. It can be considered that the ferromagnetic interaction between Ni2+ and Mn4+ gives rise to magnetic regions that pin the ferromagnetic LCMO and cause magnetic coupling at the LCMO/LNO interface.

Highlights

Shenyang National Laboratory for Materials Science, Institute of Metal Research (IMR), Chinese Academy of Sciences (CAS), 72 Wenhua Road, Shenyang 110016, China
All the layers are the perovskite phase and exhibit a (001)-preferred orientation, indicating that the LNO layer was epitaxially grown on the STO(001) substrate, and the LCMO layer was epitaxially grown on the LNO layer
The results indicate that both LCMO and LNO layers are under an in-plane tensile strain state

Summary

Introduction

D ue to the coupling of the spin, charge and orbital freedom of 3d electrons, the research area that focuses on the interfaces between dissimilar complex oxide materials is attracting considerable attention[1,2,3,4] These interfaces exhibit much richer physical connotation than conventional semiconductor heterostructures because of the novel electronic reconstruction and magnetic states. Remarkable improvement in techniques for growing and characterizing oxide thin films has opened an avenue for the study of the new interfacial electronic states at the interface between ABO3 perovskite oxides In these systems, novel physical properties such as 2-dimension (2D) superconductivities, artificial topological insulators and unexpected magnetic interaction have been found and envisaged as the promising ideal system for the realization of nanoscale oxide devices[5,6,7,8,9]. To investigate the Fermi level position at the interface can describe the charge transfer and orbital reconstruction, and further resolve the induced magnetic properties at the interface

Methods

Results

Conclusion