NMR Study of Disordered Inclusions in the Quenched Solid Helium

TL;DR

This study uses NMR to analyze disordered inclusions in quenched solid helium, revealing liquid-like inclusions that transition to a disordered glass or crystal, potentially explaining supersolid anomalies.

Contribution

First NMR investigation of disordered inclusions in quenched solid helium, identifying liquid-like phases and their transformation, linking inclusions to supersolid phenomena.

Findings

Quenched samples contain liquid-like inclusions with short T2 times.

Inclusions disappear after annealing near the melting curve.

Disordered inclusions may cause supersolid anomalies.

Abstract

Phase structure of rapidly quenched solid helium samples is studied by the NMR technique. The pulse NMR method is used for measurements of spin-lattice $T_1$ and spin-spin $T_2$ relaxation times and spin diffusion coefficient $D$ for all coexisting phases. It was found that quenched samples are two-phase systems consisting of the hcp matrix and some inclusions which are characterized by $D$ and $T_2$ values close to those in liquid phase. Such liquid-like inclusions undergo a spontaneous transition to a new state with anomalously short $T_2$ times. It is found that inclusions observed in both the states disappear on careful annealing near the melting curve. It is assumed that the liquid-like inclusions transform into a new state - a glass or a crystal with a large number of dislocations. These disordered inclusions may be responsible for the anomalous phenomena observed in supersolid region.