Electrical Resistance Study of Tb₅(Si_xGe_1-X)₄ Compounds

We studied the temperature dependence of the electrical resistivity and the magnetization in magnetic field up to 1T between 10 and 300K of the compounds Tb₅(Si_xGe_1-x)4 with x=0.6, 0.75, and 1.0. The Curie temperatures T_c were 145, 215 and 223K for samples with x=0.6, 0.75, and 1.0, respectively. All three samples exhibit irreversible changes in the electrical resistance on thermal cycling between room temperature and 10K. The irreversible effect is reduced with increasing x from 0.6 to 1.0, and it is not observed in the magnetization studies. Therefore, we conclude that the resistance irreversible effect may be due to micro-cracks formed during the thermal cycling. The difference between the zero-field-cooling and field-cooling curves, below 60K may be related to spin reorientation and coercivity. Near this temperature, the slope of the resistivity is changed from 0.3446 to 0.6355μΩcm/K for the sample with x=0.6.