02254nas a2200253 4500008004100000022001400041245010200055210006900157260007100226300001400297490000700311520133300318100002901651700002301680700002301703700001801726700002001744700002301764700001601787700002401803700001801827700002701845856012801872 2008 eng d a0897-475600aChemical inhomogeneity and mixed-state ferromagnetism in diluted magnetic semiconductor Co : TiO20 aChemical inhomogeneity and mixedstate ferromagnetism in diluted a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcFEB a1344-13520 v203 a
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.
1 aOgale, Satishchandra, B.1 aKundaliya, Darshan1 aMehraeen, Shareghe1 aFu, Lian-feng1 aZhang, Shixiong1 aLussier, Alexandre1 aDvorak, Joe1 aBrowning, Nigel, D.1 aIdzerda, Yves1 aVenkatesan, Thirumalai uhttp://library.ncl.res.in/content/chemical-inhomogeneity-and-mixed-state-ferromagnetism-diluted-magnetic-semiconductor-co-0