Observation of Melting Instability in Highly Magnetized Solid ³He

A melting instability has been observed during rapid melting of highly magnetized solid ³He. The instability occurred only if the solid is grown at low initial temperature and in high magnetic field, i.e., with high magnetization, and if the solid is melted sufficiently rapidly. After the instability of the interface occurred, the solid formed many cellular dendrites, directed parallel to the magnetic field. This is the first observation where a clear influence is seen of the magnetic field and the magnetization on a growth and melting process. The instability is attributed to a Mullins-Sekerka–type instability due to the magnetization gradient at the interface in the solid.