Impurity Spin Resonance in Antiferromagnetic FeCl2

Abstract
Electron spin resonance of Fe 3+ and Mn 2+ ions in antiferromagnetic FeCl 2 was investigated at low temperatures using various microwave frequencies and pulsed magnetic fields. Experimental results show that these impurities in FeCl 2 occupy mainly the substitutional position and couple with host Fe 2+ spins by rather weak exchange interaction. Using the metamagnetic properties of FeCl 2 , these resonances were investigated both above and below the critical field H c . The intralayer and interlayer exchange field H 1 and H 2 of these impurities were found by analysis to be