Rotating vortex core: An instrument for detecting the core excitations

TL;DR

This paper investigates how fermionic zero modes in vortex cores influence vortex dynamics, predicts NMR resonances for detecting localized states, and discusses implications for black hole thermodynamics analogies.

Contribution

It introduces a method to detect core excitations via NMR resonance and explores the effects of fermionic zero modes on vortex behavior.

Findings

Prediction of NMR resonance at interlevel frequency

Resonances can resolve localized vortex core levels

Effect depends on vortex and core rotation directions

Abstract

Effects of fermionic zero modes (bound states in a vortex core) on the rotational dynamics of vortices with sponaneously broken axisymmetry are considered. The results are compared with the Helsinki experiments where the vortex cores were driven to a fast rotation and torsional oscillations by an NMR r.f. field (Kondo et al, Phys. Rev. Lett. 67, 81 (1991)). We predict a resonance NMR absorption on localized states at the external frequency comparable with the interelevel distance, which is similar to the cyclotron Landau damping. The resonances can experimentally resolve the localized levels in vortex cores. For a pure rotation of the core, the effect depends on the relative signs of the vortex winding number and of the core rotation; thus it is sensitive to the direction of rotation of the container. The similarity with the fermionic zero modes on the fundamental strings, which simulate the thermodynamics of black holes, is discussed.