Pulsed Critical Field Measurements in Magnetic Systems

Abstract

Pulsed field magnetic moment measurements in several magnetic systems are briefly summarized. Particularly high sensitivity is attained for systems which exhibit a nonlinear variation of magnetization versus applied field, e.g., ``spin-flop.'' Changes of magnetization as small as 0.1 gauss could be observed with applied fields of over 100 kgauss under favorable circumstances. Critical fields for Cr2O3 and (Cr2O3)0.9·(Al2O3)0.1 from 4.2°K to about 0.95 TN and the corresponding calculated values of (2λK)½ are presented, where λ is the exchange constant and K is the anisotropy energy. The values of (2λK)½ agree with earlier antiferromagnetic resonance measurements in similar crystals. Results of measurements in antiferromagnetic MnF2, CoF2, and FeTiO3, and in metamagnetic FeCl2 and CoCl2 are briefly discussed. Application of the method to paramagnets is also indicated.