Fast Diffusion Process in Quenched hcp Dilute Solid $^3$He-$^4$He Mixture

TL;DR

This paper investigates the diffusion processes in quenched and annealed dilute $^3$He-$^4$He solid mixtures using NMR, revealing liquid-like inclusions in non-equilibrium samples and their disappearance after annealing.

Contribution

It demonstrates the presence of liquid-like inclusions in rapidly quenched hcp $^3$He-$^4$He mixtures and shows they vanish after annealing, advancing understanding of phase structure in these systems.

Findings

Liquid-like inclusions form during rapid quenching.

Inclusions disappear after annealing.

Diffusion coefficients distinguish phases.

Abstract

The study of phase structure of dilute $^3$He - $^4$He solid mixture of different quality is performed by spin echo NMR technique. The diffusion coefficient is determined for each coexistent phase. Two diffusion processes are observed in rapidly quenched (non-equilibrium) hcp samples: the first process has a diffusion coefficient corresponding to hcp phase, the second one has huge diffusion coefficient corresponding to liquid phase. That is evidence of liquid-like inclusions formation during fast crystal growing. It is established that these inclusions disappear in equilibrium crystals after careful annealing.