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Durham University

Department of Physics

Staff profile

Publication details for Professor Tom Lancaster

Pratt, F.L., Blundell, S.J., Lancaster, T., Brooks, M.L., Lee, S.L., Toyota, N. & Sasaki, T. (2005). μSR studies of layered organic superconductors vortex phases, penetration depth and anomalous superfluid properties. Synthetic metals 152(1-3): 417-420.

Author(s) from Durham

Abstract

Muon-spin rotation (μSR) measurements have been used to study the superconducting vortex properties of layered organic superconductors based on molecular donors such as BEDT-TTF. The μSR is particularly sensitive to the degree of local ordering of pancake vortices and can detect when the pancake layers become decoupled by intrinsic or defect-driven decoupling mechanisms, or by thermally driven motion. Further novel features of the vortex system occur when the field is tilted away from a crystal axis. Knowledge of the vortex phase behaviour allows appropriate parameter regions to be selected for reliable determination of the superconducting penetration depth λ and studies of the temperature dependence of λ have shown a T-linear term at low fields that is suppressed with increasing field. Systematic studies of λ across the range of organic superconductors have revealed a strong correlation between λ and Tc. In contrast to the linear scaling Tc ∝ λ−2 seen in high Tc cuprates, the organics show an overall correlation better described as Tc ∝ λ−3. One interpretation is that the superconducting carriers are only a small fraction of the total carrier concentration in these low-Tc superconductors. Understanding this result may give us some important clues about the nature of the superconductivity in the organics.