Magnetic Susceptibility and Low-field ESR of an Organic Ion-radical Salt, Tri-p-tolylaminiumyl Chloroantimonate

Abstract

Abstract The static magnetic susceptibility and the low-field ESR spectra (33.6 and 135 MHz) of powder samples of tri-p-tolylaminiumyl chloroantimonate were measured above 1.7 K. A broad maximum in the susceptibility, which indicates an antiferromagnetic interaction, was observed at 6.0 K; this is consistent with the results of the proton NMR measurements. In the low-field ESR spectra, broadening of the g=2 absorption line and distinct appearance of the g=4 absorption line were observed in the temperature region below Tm, the temperature at which the susceptibility is maximum. The results are interpreted by assuming that the magnetic behavior is due to antiferromagnetic Heisenberg linear chains. An abrupt decrease in the g=2 absorption intensity and a rapid increase in the g=2 absorption linewidth were also found in the temperature range from 3.5 to 2.5 K, while a slight rise in the susceptibility was observed below 2.5 K. These anomalies may imply a magnetic-phase transition in the vicinity of 2.5 K.