Experimental evidence for flux-lattice melting

Abstract

A low-frequency torsional oscillator has been used to search for flux-lattice melting in an untwinned single crystal of ${\mathrm{Y}}_{1}$${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\delta}}}$. The damping of the oscillator was measured as a function of temperature, for applied magnetic fields in the range 0.1\ensuremath{\le}H\ensuremath{\le}2.3 T. A remarkably sharp damping peak has been located. It is suggested that the temperature of the peak corresponds to the melting point of the Abrikosov flux lattice.