Optimal interface doping at La_2/3Sr_1/3MnO_3/SrTiO_3(001) heterojunctions for spintronic applications

TL;DR

This study uses ab initio calculations to identify the optimal doping level at La_2/3Sr_1/3MnO_3/SrTiO_3 interfaces, enhancing ferromagnetism and Schottky barrier height for spintronic device applications.

Contribution

It determines the optimal interlayer doping in LSMO/STO heterojunctions for improved magnetic and electronic properties, using first-principles calculations.

Findings

Optimal doping x ≈ 1/3 enhances ferromagnetism.

Largest Schottky barrier height at x ≈ 1/3.

Abrupt TiO_2 termination correlates with optimal doping.

Abstract

We examine, by means of ab initio pseudopotential calculations, La_2/3Sr_1/3MnO_3/SrTiO_3 (LSMO/STO) heterojunctions in which one unit layer of La_(1-x)Sr_xMnO_3 (with 0<x<1) is inserted at the interface. The optimal interlayer doping x for a robust interface ferromagnetism is investigated by considering the energy differences between antiferromagnetic and ferromagnetic alignment of the MnO_2-interface layer relative to bulk LSMO. The optimal doping is found to be close to x=1/3, which corresponds to an abrupt TiO_2 (001)-layer termination of STO. This is also the composition which gives the largest p-type Schottky barrier height in our calculations.