Effect of Irradiation-Induced Disorder on the Conductivity and Critical Temperature of the Organic Superconductor BEDT-TTF 2Cu SCN 2 James G. Analytis, Arzhang Ardavan, Stephen J. Blundell, Robin L. Owen, Elspeth F. Garman, Chris Jeynes, and Ben J. Powell Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom Department of Biochemistry, Uni...

In this paper, we report direct evidence of a structural transition in the organic superconductor k-~BEDT-TTF!2Cu@N~CN!2#Br near 80 K and the effect of disorder on the superconducting transition temperature. By cooling the sample from above 80 K, the interlayer magnetoresistance displays a bumplike feature, which increases sharply with increasing cooling rate. The rapidly cooled sample has a mu...

We report measurements of the de Haas–van Alphen ~DHVA! effect and ac susceptibility in the layered organic superconductor k-(BEDT-TTF)2Cu(NCS)2.The amplitude of the DHVA oscillations is attenuated over a wide field range above the irreversibility line, B irr(B), below which a rigid flux lattice is formed. Thus the DHVA effect provides a unique probe of the superconducting fluctuations at high ...

The conducting properties of the pressure-induced, layered organic superconductor (BEDT-TTF)3Cl2·2H2O have been studied at 13.5 and 14.0 kbar using low temperatures, high magnetic fields and two-axis rotation. An upper critical field that is significantly larger than that expected from the Pauli paramagnetic limit is observed when the field is applied parallel to the conducting layers. The angl...

We report the effects of uniaxial stress applied along the least conducting direction (a-axis) of the organic superconductor ~:-(BEDT-TTF)2Cu(NCS)2. We find that the superconducting transition temperature decreases With stress (dTc/dpa = 2 K/kbar). Furthermore, we find an increase in the area of the closed orbits on the Fermi sbrface with stress. These observations are at variance with predicti...

We present a resonating-valence-bond theory of superconductivity for the Hubbard-Heisenberg model on an anisotropic triangular lattice. Our calculations are consistent with the observed phase diagram of the half-filled layered organic superconductors, such as the beta, beta', kappa, and lambda phases of (BEDT-TTF)2X [bis(ethylenedithio)tetrathiafulvalene] and (BETS)2X [bis(ethylenedithio)tetras...

We have performed measurements of the microwave surface impedance Zs = Rs + iXs of the organic superconductor 1\;-(BEDT-TTF)zCu(NCS)z down to T = 0.8 K. The reactance Xs, and therefore the penetration depth A, exhibits no temperature dependence for T «Te • This result is in full agreement with calculations of the BCS ground state and gives no indication of unconventional pairing. Furthermore, w...

We describe a technique which enables angle-resolved mapping of the in-plane Fermi velocity svFd for a quasi-two-dimensional sQ2Dd conductor. The method is based on a magnetic resonance effect in the ac conductivity for in-plane magnetic fields, which has recently been successfully applied to a Q2D organic conductor. In this article, we consider the possibility of using this method to probe the...

In this paper I calculate the possible alteration of the gravitational field in a superconductor by using the time-dependent Ginzburg-Landau equations (TDGL). I compare the behaviour of a high-Tc superconductor (HTCS) like YBa2Cu3O7 (YBCO) with a classical low-Tc superconductor (LTCS) like Pb. Finally, I discuss what values of the parameters characterizing a superconductor can enhance the reduc...