Kapitza resistance in HoVO4 below 100 mK

The warmup rate of the 165Ho-enhanced nuclear spins in a HoVO4 single crystal in contact with dilute 3He is shown to be dominated by the Kapitza resistance Rμ at low bath temperature (T /SUB b/ < 100 mK). This result is obtained from an analysis of the NMR signal during the warmup, following a demagnetization which cools the sample to a temperature of about 5 mK. The temperature variation of Rμ (ο T-3 /SUB b/ ) is consitent with the acoustic mismatch model, but the magnitude is 40 times smaller than the theoretical predictions for a solid-liquid interface. The spin-lattice relaxation is also estimated, and found to be in agreement with the results of other authors