Magnetic field effects on the charge-density-wave and superconducting states in pressurized α-(BEDT-TTF)2KHg(SCN)4α-(BEDT-TTF)2KHg(SCN)4

Coupling of a magnetic field to the orbital and spin degrees of freedom of charge carriers is well known to cause suppression of superconductivity. While the orbital pair-breaking generally dominates in conventional superconductors, the Pauli paramagnetic effect may become important in some heavy fermion compounds or strongly anisotropic materials such as high-Tc or organic superconductors. The same two mechanisms are predicted to be operative also in the case of charge-density-wave (CDW) ordering. However, now they lead to opposite effects: the paramagnetic coupling weakens the CDW interaction whereas the orbital coupling enhances it in a system with an imperfectly nested Fermi surface. Here we report on the experimental evidence of both kinds of magnetic field effects on the CDW and superconducting instabilities in the layered organic metal α-(BEDT-TTF)2KHg(SCN)4α-(BEDT-TTF)2KHg(SCN)4 under quasihydrostatic pressure.