Quantum liquid of vortices in superconductors at<i>T</i>=0

Abstract

We investigate the existence of a T=0 quantum melting transition in the vortex system of a type-II superconductor. We find that homogeneous high-resistance thin films are good candidates for the observation of this effect. We calculate both the continuous dislocation-mediated melting line ${\mathit{B}}_{\mathit{m}}^{\mathit{d}}$(T) as well as the first-order melting line ${\mathit{B}}_{\mathit{m}}^{\mathit{G}}$(T) driven by Gaussian fluctuations and present the resulting H-T phase diagram. At low temperatures the melting line ${\mathit{B}}_{\mathit{m}}^{\mathit{G}}$ extrapolates to a value below the upper critical field, resulting in a quantum liquid state in the region ${\mathit{B}}_{\mathit{m}}^{\mathit{G}}$B${\mathit{H}}_{\mathit{c}2}$.