Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

TL;DR

This paper presents a nanocomposite device made of iron-oxide and graphene oxide that exhibits tunable ferromagnetism at room temperature, with adjustable transition temperature and magnetization controlled by magnetic field and electric current.

Contribution

It introduces a novel nanocomposite device with controllable magnetic properties at room temperature, including semi-permanent tunability via accessible external knobs.

Findings

Tunable transition temperature around room temperature.

Magnetization adjustable from zero to 0.011 A·m²/kg.

System retains magnetic properties until re-initialized.

Abstract

Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A.m$^2$/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite.