HIGH-FIELD STUDIES ON THE NOVEL ANTIFERROMAGNETIC STATES OF THE ORGANIC CONDUCTOR ALPHA-(BEDT-TTF)2KHG(SCN)4

We present the magnetization and Hall effect measurements at high fields perpendicular to the conducting plane of alpha-(BEDT-TTF)2KHg(SCN)4, in order to get more detailed insight into the magnetic phase diagram which we have previously proposed from the magnetoresistance measurements. The magnetization curve shows a remarkable hysteresis in the same field range where the magnetoresistance does. The de Haas-van Alphen oscillations superimposed on these magnetization are essentially reversible and drastically enhanced above the high field phase boundary. Standard analysis on the Lifshitz-Kosevich theory show no field-dependence of the effective mass, essentially constant of 1.6m0 up to above the phase boundary, but that the Dingle temperature changes from 4K to 15K discontinuously at the phase boundary. The Hall resistance shows the prominent non-linear behavior at high fields above 10T. These results are discussed and compared with those by other groups.