- Letter
Anomalously small excitation gaps as precursors of dislocation core superfluidity in solid helium-4
Phys. Rev. B 104, L060507 – Published 25 August, 2021
DOI: https://doi.org/10.1103/PhysRevB.104.L060507
Abstract
In the vicinity of the insulator-to-superfluid quantum phase transition in its core, a dislocation in a crystal supports particle-hole excitations with arbitrary small gaps. These exotic analogs of Frenkel interstitial-vacancy pairs should manifest themselves in various threshold and thermoactivation effects. In worm algorithm simulations, we reveal the presence of corresponding small gaps via the anomalous thermoactivation behavior of particle number fluctuations, which we unambiguously associate with dislocations by the “visualization” technique. Experimentally, the related threshold and thermoactivation dependencies could be observed in the ultrasound and the microwave absorption.
