High-field studies of the H-T phase diagram of α-(BEDT-TTF)2KHg(SCN)4

Detailed comparative studies of magnetoresistance and torque of α-(BEDT-TTF)2KHg(SCN)4 as a function of temperature and magnetic field in fields up to 28 T have been carried out. At high fields a phase boundary is directly shown to exist between the high- and low-temperature regions. At fields 16 ⩽ H ⩽ 21 T two maxima have been observed in the R(T) curves revealing likely two successive phase transitions. The field is shown to suppress the transition into the magnetic groundstate, at least in the low-field region.