LPE grown, substituted YIG crystals have coercivities (H c) in the 10 –1Oe range, depending on compositions and growth conditions. Dislocations, inclusions and surfaces cannot be fully responsible for the observed H c. TEM investigations of CaGeSmYIG films have revealed a periodically modulated stress field that - via magnetostrictive stresses - may explain the FMR line broadening and the measured H c. Stresses of 107 dyne cm -2 and Δa/a ~10 -5with a periodicity of 500 A produce H c ~ 1 Oe corresponding to a periodic fluctuation of Sm or Ca-Ge content by 1-3%. The mechanism, thought to be the spinodal decomposition of the garnet, causes FMR line broadening up to 200–300 Oe, i.e. more than the relaxation of Sm 3+ions.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering