Transverse and in-plane modification of superconductivity and electronic structure in the quasi-two dimensional organic conductor κ–(BEDT-TTF)2Cu(SCN)2 by uniaxial stress

We have employed uniaxial stress along the principal axes of the quasi-two dimensional organic superconductor κ–(BEDT-TTF)2Cu(SCN)2. The lattice anisotropy is thereby altered, with corresponding changes in the intermolecular transfer energies. The effect of uniaxial stress on the superconducting transition temperature Tc and critical field Bc2 is found to be anisotropic.There is an indication of an increase in Tc and Bc2 for in-plane stress, but both parameters decrease rapidly for transverse (inter-plane) stress. Magnetotransport studies reveal stress-induced changes in the Fermi surface through the observation of the Shubnikov de Haas oscillations. The stress dependence of a resistive anomaly in the magnetoresistance, which is associated with the critical field Bc2, is also investigated. We discuss the experimental findings in the context of recent phenomenological and theoretical treatments of quasi-two dimensional systems where the anisotropic triangular lattice Hubbard model has been used to treat two-dimensional superconductors.