A cavity perturbation technique is used to study the microwave response of the organic superconductor k-(BEDT-TTF)2Cu(NCS)2. Observation of a Josephson plasma resonance, below Tc (approx. 10 K), enables investigation of the vortex structure within the mixed state of this highly anisotropic, type-II, superconductor. Contrary to previous assumptions, frequency dependent studies (28 - 153 GHz) indicate that the squared plasma frequency depends exponentially on the magnetic field strength. Such behavior has been predicted for a weakly pinned quasi-two-dimensional vortex lattice [Bulaevskii et al. Phys. Rev. Lett. 74, 801 (1995)], but has not so far been observed experimentally. Our data also suggests a transition in the vortex structure near the irreversibility line not previously reported for an organic superconductor using this technique.
@article{arxiv.cond-mat/0001149,
title = {Josephson plasma resonance in k-(BEDT-TTF)2Cu(NCS)2},
author = {M. M. Mola and J. T. King and C. P. McRaven and S. Hill and J. S. Qualls and J. S. Brooks},
journal= {arXiv preprint arXiv:cond-mat/0001149},
year = {2009}
}
Comments
20 pages, including 5 figures. Revised version, accepted for publication in Phys. Rev. B