Resistive Switching and Voltage Induced Modulation of Tunneling Magnetoresistance in Nanosized Perpendicular Organic Spin Valves

TL;DR

This paper reports on nanoscale organic spin valves exhibiting large resistive switching and significant, voltage-controlled tunneling magnetoresistance, with modeling suggesting surface modifications in the ferromagnetic layer as the mechanism.

Contribution

It demonstrates voltage-induced modulation of tunneling magnetoresistance in organic spin valves, revealing a new mechanism involving surface modifications of the ferromagnetic electrode.

Findings

Resistive switching up to 4-5 orders of magnitude.

Magnetoresistance as high as -70%.

Voltage pulses can change the sign of magnetoresistance.

Abstract

Nanoscale multifunctional perpendicular organic spin valves have been fabricated. The devices based on an La$_{0.7}$Sr$_{0.3}$MnO$_3$/Alq$_3$/Co trilayer show resistive switching of up to 4-5 orders of magnitude and magnetoresistance as high as -70% the latter even changing sign when voltage pulses are applied. This combination of phenomena is typically observed in multiferroic tunnel junctions where it is attributed to magnetoelectric coupling between a ferromagnet and a ferroelectric material. Modeling indicates that here the switching originates from a modification of the La$_{0.7}$Sr$_{0.3}$MnO$_3$ surface. This modification influences the tunneling of charge carriers and thus both the electrical resistance and the tunneling magnetoresistance which occurs at pinholes in the organic layer.