Magnetic resonance within vortex cores in the B phase of superfluid $^3$He

TL;DR

This paper explores how magnetic susceptibility in superfluid $^3$He B vortex cores reveals discrete bound fermionic states, proposing magnetic resonance measurements as a direct method to probe these quantum excitations.

Contribution

It demonstrates that ac magnetic susceptibility peaks at specific frequencies related to bound fermion energy levels, offering a new way to study vortex core excitations in superfluid $^3$He B.

Findings

Magnetic susceptibility peaks at interlevel transition frequencies.

Measurement of magnetic resonance can directly probe vortex core states.

Theoretical analysis of various vortex configurations.

Abstract

We investigate a magnetic susceptibility of vortices in the B phase of multicomponent triplet superfluid $^3$He focusing on a contribution of bound fermionic states localized within vortex cores. Several order parameter configurations relevant to different types of quantized vortices in $^3$He B are considered. It is shown quite generally that an ac magnetic susceptibility has a sharp peak at the frequency corresponding to the energy of interlevel spacing in the spectrum of bound fermions. We suggest that measuring of a magnetic resonance within vortex cores can provide a direct probe of a discrete spectrum of bound vortex core excitations.