Indication of intrinsic room-temperature ferromagnetism in Ti1-xCoxO2-d thin film: An x-ray magnetic circular dichroism study

TL;DR

This study provides evidence of intrinsic room-temperature ferromagnetism in Co-doped TiO2 thin films, attributed to Co2+ ions substituting Ti4+ ions, confirmed through x-ray magnetic circular dichroism analysis.

Contribution

It demonstrates that ferromagnetism in Co-doped TiO2 arises from Co2+ ions in a specific crystal field, using XMCD and atomic-multiplet calculations, highlighting an intrinsic magnetic property.

Findings

XMCD spectra show ferromagnetic Co2+ ions at room temperature.

Spectra match atomic-multiplet calculations for high-spin Co2+ in TiO2.

Ferromagnetism is due to Co2+ ions substituting Ti4+ ions.

Abstract

Soft x-ray magnetic circular dichroism (XMCD) measurements at the Co L2,3 edges of Co doped rutile TiO2 at room temperature have revealed clear multiplet features characteristic of ferromagnetic Co2+ ions coordinated by O2- ions, being in sharp contrast to the featureless XMCD spectrum of Co metal or metallic clusters. The absorption and XMCD spectra agree well with a full atomic-multiplet calculation for the Co2+ high-spin state in the D2h-symmetry crystal field at the Ti site in rutile TiO2. The results indicate that the ferromagnetism arises from the Co2+ ions substituting the Ti4+ ions.