Oscillating nematic aerogel in superfluid 3He

TL;DR

This study investigates the oscillating behavior of nematic aerogel in superfluid helium-3, revealing a new resonance mode below the superfluid transition temperature linked to the aerogel's structure.

Contribution

It provides experimental evidence of a coupled resonance mode in superfluid helium-3 confined in nematic aerogel, advancing understanding of superfluid behavior in anisotropic porous media.

Findings

Resonance change at the superfluid transition temperature.

Emergence of an additional resonance mode below $T_{ca}$.

Coupling between the main and additional resonance modes.

Abstract

We present experiments on nematic aerogel oscillating in superfluid $^3$He. This aerogel consists of nearly parallel mullite strands and is attached to a vibrating wire moving along the direction of the strands. Previous nuclear magnetic resonance experiments in $^3$He confined in similar aerogel sample have shown that the superfluid transition of $^3$He in aerogel occurs into the polar phase and the transition temperature ($T_{ca}$) is only slightly suppressed with respect to the superfluid transition temperature of bulk $^3$He. In present experiments we observed a change in resonant properties of the vibrating wire at $T=T_{ca}$ and found that below $T_{ca}$ an additional resonance mode is excited which is coupled to the main resonance.