Electronic band-structure calculations are presented for the ferromagnetic compounds CrTe, Cr,Te, and Cr,Te,. In these compounds the Cr 3d-Te 5p covalency and the Cr 3dZz-Cr 3d12 overlap along the c axis are the most important interactions. The magnetic polarisation o f T e is parallel to the Cr local moment in CrTe, antiparallel to it in Cr,Te, and about zero in Cr,Te,. Measurementsofelectronic transport properties (resistivity. Halleffect andthermo-electricpower) andmagneticpropertiesofCr,_,)Te (6 = O.l)andCr,..,Te,(x = 0.2) indicate that these chromium tellurides are p-type metals, with strong interaction between the holes in the Te 5p band and the Cr magnetic moments. In the literature the variation of the magnetic properties of Cr? ?Te, near T, = 100 K has been attributed to a change from a canted antiferromagnetic to a collinear ferromagnetic structure. However, our Hall-effect measurements indicate that the spin structure is not collinear ferromagnetic above T,.

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The authors present investigations of the crystal structure the microstructure and the magnetic properties of the inter-metallic compounds XMnSb (X=Pt, Ni, Co, Au, Cu) and PtMnSn. It was found that several of these materials contain precipitates of other phases and/or large atomic disorder, which can be influenced by heat treatment. The magnetic properties show an effective paramagnetic moment which differs from the value corresponding to the saturation moment at 0 K. This effect is attributed to a decrease of the conduction electron spin polarisation at high temperature.

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For pt.I see ibid., vol.1, p.2341 (1989). The electrical resistivity and the Hall effect of inter-metallic compounds XMnSb (X=Pt, Ni, Au) and PtMnSn were investigated in the temperature region 4-1000 K. The results for the anomalous Hall effect were analysed in terms of skew scattering and side-jump contributions. This analysis is possible in a half-metallic ferromagnet because the conduction electron spin polarisation at T=0 K is known.

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