FIELD-DEPENDENT MAGNETIC DIFFUSE-SCATTERING FROM THE SPIN-GLASS (MN, MG)S

The peculiarity of the spin glass system (Mn,Mg)S stems from the domin ation of Heisenberg-type magnetic interactions. Past theoretical calcu lations of spin glass systems involving Heisenberg interactions predic t a spin glass transition only at T = 0 K. Magnetic susceptibility mea surements show temperature hysteresis along with anomalies in the FC s usceptibility that correspond to the freezing temperature. Diffuse mag netic neutron scattering measurements were performed on the LONGPOL in strument at a temperature above T-f under different applied magnetic f ields. Magnetic short-range order parameters were calculated from a fi t to the data. The measured magnetic moment per Mn atom is about 5.4 m u(B). Under different applied magnetic fields, the nearest-neighbor co rrelations do not change. But the kappa-independent scattering does sh ow a significant change. Magnetic susceptibility measurements also sho w an applied field dependence. Magnetic susceptibility measurements ca n be converted to a generalized susceptibility at kappa = 0. They also show an applied field dependence similar in magnitude to the kappa-in dependent scattering. (C) 1998 Published by Elsevier Science B.V. All rights reserved.