Analog control of electrical conductivity in La0.5Sr0.5FeO3-{\delta} through oxygen deficiency induced magnetic transition

TL;DR

This study demonstrates precise, analog control of electrical conductivity in La0.5Sr0.5FeO3-{eta} thin films via oxygen vacancy manipulation, inducing a magnetic transition and enabling magnetoelectric coupling with a ferromagnetic layer.

Contribution

It introduces a method for continuous, voltage-controlled modulation of oxygen stoichiometry in oxide thin films, revealing a magnetic transition that affects electrical and magnetic properties.

Findings

Over 4 orders of magnitude change in conductivity achieved.

Magnetic transition from paramagnetic to antiferromagnetic observed.

Control over exchange interaction with a ferromagnetic layer demonstrated.

Abstract

Switchability of materials properties by applying controlled stimuli such as voltage pulses is an emerging field of study with applicability in adaptive and programmable devices like neuromorphic transistors or non-emissive smart displays. One of the most exciting approaches to modulate materials performance is mobile ion/vacancy insertion for inducing changes in relevant electrical, optical, or magnetic properties, among others. Unveiling the interplay between changes in the concentration of mobile defects (like oxygen vacancies) and functional properties in relevant materials represents a step forward for underpinning the emerging oxide iontronics discipline. In this work, electrochemical oxide-ion pumping cells were fabricated for an analog control of the oxygen stoichiometry in thin films of mixed ionic-electronic conductor La0.5Sr0.5FeO3-{\delta}. We demonstrate over more than 4 orders of magnitude electronic conductivity control within the same crystallographic phase through the precise and continuous voltage control of the oxygen stoichiometry. We show that behind the modification of the transport properties of the material lays a paramagnetic-to-antiferromagnetic transition. We exploit such magnetoelectric coupling to show control over the exchange interaction between La0.5Sr0.5FeO3-{\delta} and a ferromagnetic Co layer deposited on top.