New Electronic Phase Transitions in \alpha-(BEDT-TTF)2KHg(SCN)4

摘要

\alpha-(BEDT-TTF)2KHg(SCN)4 is considered to be in the charge-density-wave(CDW) state below 8 K. We present new magnetoresistance data suggesting thatthe material undergoes a series of field-induced CDW (FICDW) transitions atpressures slightly exceeding the critical pressure Pc at which the zero-fieldCDW state is destroyed. Further, we argue that a novel kind of FICDWtransitions, entirely determined by a superposition of the strong Pauli andquantizing orbital effects of magnetic field on the CDW wavevector, arises whenthe field is strongly tilted towards the conducting layers. These newtransitions can take place even in the case of a relatively well nested Fermisurface. Finally we report on the superconducting (SC) state and itscoexistence with the CDW in the title compound under quasi-hydrostaticpressure. Below Pc the material is most likely a heterogeneous SC/CDW mixture,with the SC phase persisting down to ambient pressure. The SC onset temperatureappears to drastically increase upon entering the SC/CDW coexistence region.