Interface driven magnetoelectric effects in granular CrO2

TL;DR

This paper investigates how surface layers of Cr2O3 on granular CrO2 influence its magnetoelectric properties, revealing temperature-dependent effects and potential for device applications.

Contribution

It demonstrates the presence of Cr2O3 surface layers on CrO2 grains and links their magnetoelectric effects to the overall properties of the system.

Findings

Cr2O3 surface layers are present on CrO2 grains.

Magnetoelectric susceptibility shows a sign change around 100 K.

Finite magnetoelectric susceptibility observed near room temperature.

Abstract

Antiferromagnetic and magnetoelectric Cr2O3-surfaces strongly affect the electronic properties in half metallic CrO2. We show the presence of a Cr2O3 surface layer on CrO3 grains by high-resolution transmission electron microscopy. The effect of these surface layers is demonstrated by measurements of the temperature variation of the magnetoelectric susceptibility. A major observation is a sign change at about 100 K followed by a monotonic rise as a function of temperature. These electric field induced moments in CrO3 are correlated with the magnetoelectric susceptibility of pure Cr2O3. This study indicates that it is important to take into account the magnetoelectric character of thin surface layers of Cr2O3 in granular CrO2 for better understanding the transport mechanism in this system. The observation of a finite magnetoelectric susceptibility near room temperature may find utility in device applications.