Paul Goddard

Abstract:

(BEDT-TTF)3[MnCr(C2O4)3] is the first ferromagnetic molecular metal, in which organic layers of BEDT-TTF alternate with infinite layers of the bimetallic oxalate complex [MnCr(C2O4)3]-. While the bimetallic layer undergoes a magnetic phase transition into a canted ferromagnetic state at 5.5 K, the metallic character of the conductivity is not affected by the magnetic transition [Nature 408 (2000) 447]. We performed magnetoresistance measurements (B≤17 T) at low temperatures (T≥900 mK) and under hydrostatic pressures of up to 2.0 GPa. Oscillations in the magnetoresistance develop under pressure that can be interpreted as Shubnikov-de Haas oscillations, if an internal magnetic field is taken into account. These measurements can thus be interpreted as a measure of the internal magnetic field in the conduction layer caused by the adjacent magnetic oxalate layers. © 2002 Elsevier Science B.V. All rights reserved.

Abstract:

A brief review of some of the arguments pointing towards the possibility of organic conductors of the form alpha-(BEDT-TTF)(2)MHg(SCN)(4) (where M = K, Tl and Rb) being candidates for Frohlich superconductivity is given. (C) 2002 Published by Elsevier Science B.V.

Abstract:

Peaks in the interlayer magnetoresistance of the layered superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) are observed in the presence of an exactly in-plane magnetic field. The existence of these resistance peaks implies the presence of a three-dimensional Fermi surface extending in the interlayer region. Analysis of the width of the peaks yields a value for the interlayer transfer integral. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract:

The interlayer transfer integrals of various organic superconductors have been deduced using high-magnetic-field techniques. The measurements demonstrate the inappropriateness of criteria used to denote incoherent interlayer transport.

Abstract:

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 angle-dependent magnetoresistance suggests incoherent transport between the conducting layers at both pressures and the observed negative magnetoresistance at 13.5 kbar can be explained by considering Anderson localization within the layers. Further application of pressure destroys the effects of localization.