Theory of the Anomalous Nuclear Spin Relaxation in U2D2 Solid ³He

Abstract

In pulsed NMR experiments on U2D2 solid ³ He it has been observed that in some cases free induction signals decay very quickly. It was also found that in such cases a large negative frequency shift from the Larmor frequency appears. We investigated the mechanism of this anomalous nuclear spin relaxation theoretically, using the Holstein-Primakoff method for the Hamiltonian including dipole and exchange interaction. It is shown that the “Suhl Instability” which had been observed only in the electron spin systems occurs also in the nuclear spin systems and these observed behaviors are attributed to the instability of the uniform precession of magnetization due to the excitation of spin waves.