B-T-P phase diagram of #alpha#-(BEDT-TTF)_2KHg(SCN)_4

摘要

We present detailed studies of the B-T-P phase diagram of #alpha#-(BEDT-TTF)_2KHg(SCN)_4 by means of magnetic torque and magnetoresistance measurements. The phase diagram for magnetic field oriented almost perpendicular to the highly conducting layers closely resembles that expected for a charge-density-wave (CDW) system with an imperfectly nested Fermi surface. The influence of pressure can be readily understood as deteriorating the nesting conditions and thus enhancing the role of the orbital effect of magnetic field. At field strongly tilted from the normal to the layers, both the torque and magnetoresistance display a number of irreversible features that may be associated with a series of first-order phase transitions. This behaviour is not understood within the existing CDW theories.