Nuclear Spin Relaxation in Gallium Metal

The nuclear spin-lattice relaxation time $T_1$ has been measured in a fine powder of gallium metal from near the superconductivity transition temperature 1.1°K to near the melting point 307°K. The experiments were performed with pure nuclear quadrupole resonance using pulsed-nuclear-resonance techniques. Between approximately 4.2 and 300°K the product of $T_1$ and the absolute temperature is found to be temperature-dependent, varying from 1.01 sec°K between 1.1 and 4.2°K to 0.73 sec°K at 300°K. The relaxation mechanism is magnetic in origin, as determined from the ratio of the relaxation times for the ${\mathrm{Ga}}^{69}$ and ${\mathrm{Ga}}^{71}$ nuclei. Various explanations for the temperature dependence of $T_{1}T$ are discussed.