Mechanical measurement for phase transition of vortex at low field in high-Tc cuprates

Abstract

The resonance frequency ω and internal friction (IF) Q -1 of Y-Ba-Cu-O single crystal, Bi system, Hg system and Tl system polycrystalline were measured between 77k and 120k in different applied field up to 0.5T. A dissipation peak can be found below Tc in all samples. In order to clarify the mechanism of the dissipation peak, the measurement were performed as functions of different vibrating frequency and vibrating amplitude. No obvious dissipation peak shift occurs in the frequency range from 10 2 to 10 3 Hz, the dissipation peak height is obviously frequency dependent and satisfies the power law Q -1 ∝ω -1 . This is speculated to originate from phase transition associated with the melting or a glass-transition of vortex. These results provide a fundamental measurement of the phase diagram of vortex in high-Tc cuprates.