Orbital glass and spin glass states of 3He-A in aerogel

TL;DR

This paper investigates the orbital and spin glass states of superfluid 3He-A in aerogel, revealing how anisotropic deformation and resonant excitation influence the formation and properties of these glass phases.

Contribution

It provides a combined theoretical and experimental analysis of orbital and spin glass phases in superfluid 3He-A within anisotropic aerogel, highlighting new metastable states induced by RF excitation.

Findings

Identification of two distinct orbital glass phases with different spin structures.

Demonstration of metastable spin-glass phase induced by RF excitation.

Measurement of anisotropy parameters via NMR signatures.

Abstract

Glass states of superfluid A-like phase of 3He in aerogel induced by random orientations of aerogel strands are investigated theoretically and experimentally. In anisotropic aerogel with stretching deformation two glass phases are observed. Both phases represent the anisotropic glass of the orbital ferromagnetic vector l -- the orbital glass (OG). The phases differ by the spin structure: the spin nematic vector d can be either in the ordered spin nematic (SN) state or in the disordered spin-glass (SG) state. The first phase (OG-SN) is formed under conventional cooling from normal 3He. The second phase (OG-SG) is metastable, being obtained by cooling through the superfluid transition temperature, when large enough resonant continuous radio-frequency excitation are applied. NMR signature of different phases allows us to measure the parameter of the global anisotropy of the orbital glass induced by deformation.