Superfluid 3He in squeezed nematic aerogel

TL;DR

This study investigates superfluid 3He in nematic aerogel with and without squeezing, revealing how anisotropy affects the polar-distorted A phase and its NMR properties, providing insights into the orbital order parameter.

Contribution

It demonstrates the impact of mechanical squeezing on the anisotropy of the 2D LIM state in superfluid 3He within nematic aerogel, and how this influences NMR signatures.

Findings

Polar phase transition occurs in both samples.

Squeezing induces anisotropy in the 2D LIM state.

Anisotropy affects NMR properties and phase markers.

Abstract

We present results of nuclear magnetic resonance (NMR) experiments in superfluid 3He in two samples of nematic aerogel consisting of nearly parallel mullite strands. The samples were cut from the same piece of the aerogel, but one of them was squeezed by 30% in the direction transverse to the strands. In both samples the superfluid transition of 3He occurred into the polar phase, where no qualitative difference between NMR properties of 3He in these samples was found. The difference, however, has appeared on further cooling, after the transition to the polar-distorted A phase (PdA phase) with the orbital part of the order parameter in the 2D Larkin-Imry-Ma (LIM) state. In the squeezed sample the 2D LIM state is anisotropic that results in changes in the NMR, which can be used as an additional marker of the PdA phase and have allowed us to measure the value of the anisotropy.