Application of spin-wave theory to EuS

Abstract

Magnetization data for EuS powder in zero field and at liquid-helium temperatures has been obtained by nuclear magnetic resonance of both the Eu151 and Eu153 nuclei. These data are considered simultaneously with those for the specific heat of EuS powder obtained by McCollum and Callaway in order to provide a more definitive application of the spin-wave theory to this material. The theory is that given by Holstein and Primakoff and special attention is given to the effects of magnetic dipolar coupling on the spin-wave energy and moment. The calculation was carried out by summation over the exact Brillouin zone. Values of the nearest-neighbor exchange interaction J1 and second-neighbor exchange J2, as well as an effective field H which simultaneously produced reasonable agreement between calculation and experiment are J1=0.20±0.01°K, J2=-0.08a″0.02°K and H=4.0±0.2 kOe. These values are fairly consistent with other parameters known for EuS. © 1964 The American Physical Society.