Viscoelasticity and surface tension at the defect-induced first-order melting transition of a vortex lattice

Abstract

We show that thermally activated interstitial and vacancy defects can lead to first-order melting of a vortex lattice. We obtain good agreement with experimentally measured melting curve, latent heat, and magnetization jumps for ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ and ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{CaCu}}_2{\mathrm{O}}_8.$ The shear modulus of the vortex liquid is frequency dependent and crosses over from zero at low frequencies to a finite value at high frequencies. We also find a small surface tension between the vortex line liquid and the vortex lattice.