IMPURITY SPIN RESONANCE IN ANTIFERROMAGNETIC COCL22H2O

Electron spin resonance of Mn2+ ions in antiferromagnetic CoCl22H2O was investigated using microwaves and pulsed magnetic fields. The results indicate that the Mn2+ ion couples with surrounding Co spins by relatively weak exchange interactions and the effective spin Hamiltonian can be written by H=g0μB(H0+HE)S0+DS20z, where the first term represents the Zeeman energy of the impurity spin So under an external magnetic field H0 and the resultant effective field HE coming from the neighboring Co spins. By analyzing the experimental results, three exchange constants J0′, J1′ and J2′ are obtained as J0′(F)=0.59±0.04 cm-1, J1′(AF)=0.73±0.02 cm-1 and J2′(AF)=0.23±0.03 cm-1, where F and AF mean the ferromagnetic and antiferromagnetic coupling, respectively. D was determined to be -0.13±0.01 cm-1. © 1968, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.