On a "Robust" A-like State of $^3He$ in Aerogel

TL;DR

This paper investigates a quasi-isotropic ESP phase of superfluid $^3He$ in aerogel, proposing a modified state that aligns better with experimental splitting asymmetry observations under magnetic fields.

Contribution

It introduces a quasi-isotropic ESP phase with unequal amplitudes, providing a model that better matches experimental data on splitting asymmetry in aerogel.

Findings

The quasi-isotropic ESP phase can explain the observed splitting asymmetry.

Equal amplitude ESP state does not match experimental asymmetry.

Modified state reconciles theoretical predictions with experimental results.

Abstract

The orbitally isotropic Equal Spin Pairing (ESP) state has been proposed in Ref. [1] as a candidate of an A-like phase of superfluid $^3He$ in aerogel environment. In order to preserve an exact isotropy of the state in the presence of the magnetic field the condensate with equal values of the amplitudes $\Delta_{\uparrow\uparrow}$ and $\Delta_{\downarrow\downarrow}$ was adopted. Experimentally it is established that this version does not reproduce observed splitting asymmetry of ESP phase in aerogel under the action of an external magnetic field. Here we explore the behavior of the quasi-isotropic version of an axiplanar ESP phase with $\Delta_{\uparrow\uparrow}\neq \Delta_{\downarrow\downarrow}$ and show that for this state the splitting asymmetry ratio could be reconciled with experimental observations.