Magnetic-field effects on the reentrance transition of alloy of pristine and fully deuterated (DMcDCNQI)2Cu

The electrical resistance and the heat capacity were measured in the title compound under magnetic fields in the metal-insulator-metal re-entrance transition regime. The magnetoresistance shows normal behavior characteristic of simple metals. Also the heat capacity shows no enhancement. Therefore no support is given to the possible interpretation of the re-entrance transition in terms of the heavy electron state. It is found, however, that the magnetic field induces a first order transition from the metallic to the insulating phases when the system is close to the phase boundary. This is ascribed to the lowering of the insulating phaseʹs free energy because of the Zeeman energy of Cu2+ spins present in the insulating phase.