Influence of Paramagnetic Resonance on the Static Susceptibility. Spin—Lattice Relaxation Time of Cupric Sulfate Pentahydrate

Publisher Website
Google Scholar
Abstract
The static direct-current susceptibility of cupric sulfate pentahydrate was measured as a function of microwave power absorbed at electron spin resonance. This technique was used to study the spin relaxation process of cupric sulfate pentahydrate as a function of temperature, microwave power level, and crystal size. Up to less than one-half saturation, the relaxation time τ1 was found to be independent of the degree of saturation and inversely proportional to the temperature τ1T=0.2 sec·°K, showing that the predominant mechanism at liquid-helium temperatures is the direct spin—lattice process. At high saturation levels there is evidence of crystal heating. These results are compared with those obtained by the cw saturation method on cupric sulfate pentahydrate, and the discrepancy in the magnitude of the relaxation time and its temperature and power dependencies are explained. This new technique is shown to be especially useful for studying power-transfer mechanisms in concentrated spin systems.