Reversible switching of room temperature ferromagnetism in CeO2-Co nanoparticles

TL;DR

This study demonstrates reversible room temperature ferromagnetism in CeO2-Co nanoparticles, controllable via thermal treatments that modulate oxygen vacancies, offering potential for tailored magnetic materials.

Contribution

It reveals a reversible control of ferromagnetism in CeO2-Co nanoparticles through thermal treatments, linking magnetic behavior to oxygen vacancy manipulation.

Findings

Ferromagnetism can be switched on and off by thermal treatments in vacuum and oxidizing conditions.

The ferromagnetic contribution increases with longer vacuum thermal treatments.

A direct relation between oxygen vacancies and ferromagnetism is established.

Abstract

We investigated the reversible ferromagnetic (FM) behavior of pure and Co doped CeO2 nanopowders. The as-sintered samples displayed an increasing paramagnetic contribution upon Co doping. Room temperature FM is obtained simply by performing thermal treatments in vacuum at temperatures as low as 500^{\circ}C and it can be switched off by performing thermal treatments in oxidizing conditions. The FM contribution is enhanced as we increase the time of the thermal treatment in vacuum. Those systematic experiments establish a direct relation between ferromagnetism and oxygen vacancies and open a path for developing materials with tailored properties.