Abstract
We study angular-dependent magnetoresistance in a low- layered cuprate . The low K allows complete suppression of superconductivity by modest magnetic fields and facilitates accurate analysis of the upper critical field . We observe a universal exponential decay of fluctuation conductivity in a broad range of temperatures above and propose a method for extraction of from the scaling analysis of the fluctuation conductivity at . Our main result is observation of a surprisingly low anisotropy , which is much smaller than the effective mass anisotropy of the material . We show that the anisotropy is decreasing with increasing field and saturates at a small value when the field reaches the paramagnetic limit. We argue that the dramatic discrepancy of high-field and low-field anisotropies is clear evidence for paramagnetically limited superconductivity.
- Received 20 February 2014
- Revised 12 June 2014
DOI:https://doi.org/10.1103/PhysRevB.89.214516
©2014 American Physical Society