Towards ordered flux flow in A15 superconductor V$_{3}$Si at high fields

ORAL

Abstract

The motion of flux quanta is observed in a high-quality superconducting single crystal of V$_{3}$Si with weak pinning and significantly reduced thermal fluctuations due to a critical temperature of less than 17 K. This opens up the possibility of approaching ordered, Bardeen-Stephen flux flow (BSFF). The flux flow resistivity \textit{$\rho $}$_{ff}$ associated with dissipative flux motion is observed in V-I curves as a high-current transition to an ohmic curve whose dissipation level is \textit{below} the normal-state level. Details of overcoming technical difficulties of using high currents are described. BSFF is expected to be manifested by a linear dependence of \textit{$\rho$}$_{ff}$ on applied field $H$. Measuring from fields of 6 T up to 20 T, an approach to ohmic curves characteristic of BSFF are clearly distinguishable, along with other interesting features such as the ``peak'' effect in critical current $J_{c}(H)$ seen only when the pinning energy density is comparable to the elasticity of the flux medium. This and further data and their interesting ramifications are discussed.

Authors

  • R. Khadka

    University of South Alabama

  • A. A. Gapud

    University of South Alabama

  • Arneil Reyes

    National High Magnetic Field Laboratory, National High Magnetic Field Laboratory 32310, Department of Physics and National High Magnetic Field Laboratory, Florida State University, National High Magnetic Field Lab

  • L. Lumata

    National High Magnetic Field Laboratory

  • Phillip Kuhns

    National High Magnetic Field Laboratory, National High Magnetic Field Laboratory 32310, Department of Physics and National High Magnetic Field Laboratory, Florida State University, National High Magnetic Field Lab

  • D. K. Christen

    Oak Ridge National Laboratory, ORNL