ELECTRON SPIN RESONANCE STUDY OF SOME INSULATING EUROPIUM CHALCOGENIDE SPIN GLASSES.

ESR in insulating spin glasses is of interest because skin effect and relaxation via conduction electrons are absent. The high temperature line widths have been correctly ascribed to exchange narrowed dipolar broadening (7). Recently Levy and Raghavan have used the Kubo-Tomita formalism to account for the concentration and frequency dependences and the Mori-Kawasaki formalism to account for the temperature dependence of line widths (5). In this report, additional data on Eu//xSr//1// minus //xS, Eu//xBa//1// minus //xS and the micromagnetic EuS//ySe//1// minus //y compounds are presented. Detailed comparison of the line widths with the computed values from the above theory is also made.