Torque measurements in underdoped Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$ single crystals

ORAL

Abstract

We report in-plane and out-of-plane angular-dependent torque measurements on underdoped Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$ single crystals both below and above the zero-field superconducting transition temperature $T_{c}(0)$ and in applied magnetic fields $H$ up to 14 T. The out-of-plane torque data show that a diamagnetic signal persists into the normal state, which is consistent with previous reports on Bi$_2$Sr$_2$Ca$_2$CuO$_{8+\delta}$. These data also reveal that the vortex matter in the superconducting state has lower dimensionality compared to the one in the normal state. Furthermore, in-plane torque measurements show that the presence of vortices above $T_c(0)$ destroys the phase coherence of the Cooper pairs.

*This research was supported by the National Science Foundation under Grant No. DMR-1006606 at KSU. TH acknowledge the support of ICAM Branches Cost Sharing Fund from the Institute for Complex Adaptive Matter.

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Authors

  • T. Hu

    • Kent State University, Kent, Ohio, USA and University of California, Davis, CA, USA

  • H. Xiao

    • Kent State University, Kent, Ohio, USA and Institute of Physics, Beijing, China

  • P. Gyawali

    • Kent State University, Kent, Ohio, USA

  • H.H. Wen

    • Institute of Physics, Beijing, China

  • C.C. Almasan

    • Kent State University, Kent, Ohio, USA