Spin resonance in Eu(x)Sr(1-x)S with x-0.4, 0.5, and 0.54.

Electron spin resonance has been studied in single crystal spheres of Eu(x)Sr(1-x)S with samples of nominal composition x = 0.4, 0.5 and 0.54. The emphasis has been on the field for resonance of x = 0.4 material at 11.65 GHz at temperatures between 4.2 and 1.65K. Even at the lowest temperatures the lines do not vary with crystal orientation. In all samples there is a depression of the field for resonance beginning at about 10K, and increasing to the lowest temperatures. This is interpreted as an "internal" field H(i). Measurements at 17 GHZ reveal that H(i) for all three compositions decreases with increasing frequency.