The spin-lattice relaxation of ${}_{}{}^{60}{}_{}{}^{}\mathrm{Co}$ nuclei in an iron host has been studied in various applied magnetic fields using the technique of nuclear magnetic resonance on oriented nuclei. In this method the nuclei studied are those in the bulk of the domains. The measurements show that the relaxation rate is dependent on the state of magnetization of the sample; the rate in 0.4 kOe is nearly five times faster than that measured in 6.7 kOe. This result agrees with previous measurements using conventional nuclear magnetic resonance, and demonstrates unambiguously the existence of a relaxation process in multidomain transition-metal ferromagnets that has never been adequately explained by theory. The resonance linewidths measured in the experiments show a dependence on the applied field. At high fields, when the sample is magnetically saturated, the full width at half maximum is about 0.7 MHz, while in the lowest field employed this width is only 0.2 MHz. An explanation in terms of demagnetizing effects is offered.

• Received 14 August 1973

DOI:https://doi.org/10.1103/PhysRevB.9.2165