HIGH-FIELD MAGNETIZATION MEASUREMENTS ON ALPHA-(BEDT-TTF)(2)KHG(SCN)(4)

We report measurements of the steady and oscillatory part of the magnetization by means of a torquemeter at temperatures down to 0.4K and magnetic fields up to 28T. Below 24T we find the well known splitting in the de Haas van Alphen- (dHvA-) oscillations for T less than or equal to 1K and Theta less than or equal to 25 degrees, where Theta is the angle between the magnetic field and the normal to the layers. The phase transition at 24T is indicated by a strong increase of the dHvA amplitude. At low fields the steady torque shows a quadratic dependence on B, whereas in the high field regime a complex dependence on the temperature and the angle Theta is observed. For Theta greater than or equal to 60 degrees several field induced anomalies occur up to the maximal field of 28T for temperatures well below 4K. But also for small values of Theta our experiments show evidence for a complex magnetic groundstate at 28T for temperatures below 1K.