Crystal Growth and Melting of Nuclear-Ordered Solid 3He

We measured crystal growth and melting rate of nuclear-ordered solid 3 He in a rectangular sample cell. The melting rate was much faster than the growth rate at all temperatures in the low field phase (U2D2) and strongly depended on temperature. The melting occurred on a rough surface and the dissipation mechanism of the melting was compared with the surface magnon scattering mechanism. The crystal growth rate did not depend on temperature and was compared with the spiral growth model associated with screw-dislocations. We found that a large chemical potential difference started to develop when the crystal grew large enough so that the sample became almost single domain at the upper part of the sample cell. We attributed this saturation to the pinning of the screw dislocation on the sample wall. This chemical potential difference decreased rapidly when the crystal was in the high field phase and the crystal grew as it did before the saturation. The crystal continued to grow even after the crystal returned to the U2D2 phase from the high field phase.