We report results on experimental and theoretical studies of structural and magnetic properties of (formula presented) nanocomposite films. It was found for films prepared by magnetron sputtering with subsequent annealing that lattice parameters a and c of fct FePt change with significantly different rates with increase of the (formula presented) fraction. As a consequence, fundamental magnetic properties change markedly, with the Curie temperature decreasing by 36% for 25% FePt volume fraction compared with the bulk value. Using an ab initio parametrization of magnetic interactions, we propose statistical model of thermal fluctuations in fct FePt, which explains these observations. Our modeling results demonstrate that the observed phenomena originate in the variation of the exchange interaction parameters with the changes in the (formula presented) ratio. We find that the main factor of this variation is the increase of the difference between the in-plane and interplane exchange interactions as (formula presented) decreases from its bulk value due to stress exerted by the (formula presented) matrix.
|Original language||English (US)|
|Number of pages||6|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 2002|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics