High field magnetization measurements on α-(BEDT-TTF)2KHg(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 ≤ 1K and Θ ≤ 25°, where Θ 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 Θ is observed. For Θ ≥ 60° several field induced anomalies occur up to the maximal field of 28T for temperatures well below 4K. But also for small values of Θ our experiments show evidence for a complex magnetic groundstate at 28T for temperatures below 1K.