Diluted Magnetic Semiconductors in High Magnetic Fields |
| Y. Shapira Department of Physics, Tufts University, Medford MA 02155, USA and GES, Université Montpellier II, Place E. Bataillon, 34095 Montpellier Cédex 5, France |
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| Magnetization studies of diluted magnetic semiconductors in high fields are reviewed. Magnetization steps due to pairs were originally used to measure the near neighbor exchange constant J1. They are now also used to determine: (1) the smaller exchange constants J2 and J3, (2) the difference between J1's for inequivalent near neighbors in wurtzite diluted magnetic semiconductors, and (3) the Dzyaloshinski-Moriya interaction. A different type of magnetization step, due to isolated ions, is used to determine the uniaxial anisotropy of Co++ ions in wurtzite diluted magnetic semiconductors. In Fe-based diluted magnetic semiconductors the high-field magnetization exhibits two effects: (1) strong dependence on field direction in cubic diluted magnetic semiconductors, and (2) reversal of the uniaxial magnetization-anisotropy in wurtzite diluted magnetic semiconductors. In (100) EuTe/PbTe superlattices the antiferromagnetic transition, both at zero and finite H, is depressed when the EuTe layer becomes only a few monolayers thick. The easy directions are in the (100) plane of the layer, which is explained by the dipole-dipole anisotropy. |
| DOI: 10.12693/APhysPolA.87.107 PACS numbers: 75.50.Pp, 75.30.Et, 75.70.Fr |