H.-U. Mueller

Energy level crossing effects in the rare-earth zircons TmPO4 and PrVO4

High-field magnetization measurements using the single-turn coil technique not only give detailed information on the critical magnetic field of level crossing anomalies in the rare-earth zircons TmPO4 and PrVO4, but also provide strong evidence of hysteresis effects in up- and down-sweep of the external magnetic field.

The Megagauss facility of the HUMBOLDT high magnetic field center in Berlin

Abstract We report on concept. realisation, and first experimental results obtained with the preliminary megagauss equipment of the HUMBOLDT High Magnetic Field Center. The present megagauss set-up is a handy, transportable single-turn coil equipment using only 20% of the capacity of the final installation, i.e. 50 kJ at 60 kV producing about 100 and 200 T in the single-turn coils of 10 and 5 mm diameter, respectively. Test reports on magnetooptical measurements at low temperature are presented.

Intra- and inter-band transitions in HgSe in megagauss fields

Abstract IR-megagauss spectroscopy on HgSe provides information on both intra- and inter-band transitions resulting in a new set of k*p-parameters for high magnetic field application. Transient effects in the resonance intensities are due to hysteresis effects in the spin dependent population and provide a novel tool for the determination of the spin-lattice relaxation.

Spin dynamics in megagauss fields

Transient magnetic fields in the megagauss regime prove as a new tool to investigate detailed information on spin-lattice relaxation using the delayed population change of the spin levels in the presence of rapidly varying magnetic fields. The method is applied to HgSe and HgTe epitaxial layers in magnetic fields up to 150 T.

Investigation of HgSe/HgSe:Fe quantum wells and super lattices

High-field magnetospectroscopy measurements on HgSe/HgSe :Fe quantum wells and superlattices are reported. Fe 2+ substitution of Hg 2+ manifests itself in a donor about 210 meV above the conduction band edge and thus for sufficiently high carrier concentration as a Fermi level pinned system in the mixed valence regime. The MBE-grown samples on ZnTe/GaAs substrates exhibit 2D effects for characteristic well or superlattice dimensions < 20 nm. Strong anisotropy effects due to strain are observed. By variation of the size quantization the predicted transition from a 2D to 3D QHE for Fermi level pinned systems is demonstrated.