Magnetotransport Properties and Spin Textures in Gd5Ge4

We report on resistivity, magnetoresistance and Hall effect experiments in the magnetocaloric compound Gd
5
Ge
4
. Measurements were carried out in several temperatures in magnetically ordered state and in the paramagnetic phase. Attention is also given to the temperature domain where a Griffiths-type phase was identified. The resistivity versus temperature experiments are strongly dependent on thermal and magnetic cycling of the sample. These results indicate a polyfleration of microcracks in the sample under cycling or the occurrence of a phase separation phenomenon. At the low temperature limit the magnetoresistance is positive and dominated by the spin-mixing effect. In the intermediate temperature range the magnetoresistance is negative and reaches giant values. The Hall effect at low temperatures shows a peaked contribution that suggests the occurrence of a field-induced transition from the antiferromagnetic ground state to a ferromagnetic ordering. In the paramagnetic phase, the ordinary Hall effect is hole-like.