Chemical inhomogeneity and mixed-state ferromagnetism in diluted magnetic semiconductor Co : TiO2

TitleChemical inhomogeneity and mixed-state ferromagnetism in diluted magnetic semiconductor Co : TiO2
Publication TypeJournal Article
Year of Publication2008
AuthorsOgale, SB, Kundaliya, D, Mehraeen, S, Fu, L-feng, Zhang, S, Lussier, A, Dvorak, J, Browning, ND, Idzerda, Y, Venkatesan, T
JournalChemistry of Materials
Volume20
Issue4
Pagination1344-1352
Date PublishedFEB
Type of ArticleArticle
ISSN0897-4756
Abstract

Diluted magnetic semiconductors (DMS) are among the most intensely investigated materials in recent times in view of their great application potential. Yet, they are also the most controversial because of the possibility of extrinsic effects attributable to dopant solubility and clustering, point defects, incorporation of unintentional impurities, etc. This has highlighted the central role of materials chemistry in rendering a specific microstate and property response. In this work, we provide a combined window of high-resolution scanning transmission electron microscopy and electron energy-loss spectrometry, X-ray absorption (XAS)/X-ray magnetic circular dichroism (XMCD), and magnetization measurements on epitaxial rutile CoxTi1-xO2 (x = 0-0.06) system (the first discovered oxide-DMS, which continues to be controversial) grown at low temperature (400 degrees C) under different ambient atmospheres. The study brings out a mixed-state scenario of ferromagnetism involving intrinsic DMS (uniform dopant distribution at low dopant concentration) and coupled cluster magnetism, involving cobalt associations within the matrix at higher concentrations. We also show that by matrix valence control during growth, it is possible to realize a uniform embedded cluster state and the related coupled cluster magnetism.

DOI10.1021/cm702089z
Type of Journal (Indian or Foreign)Foreign
Impact Factor (IF)9.407
Divison category: 
Physical and Materials Chemistry