Electrical resistivity of the singlet-ground-state systemTbcY1−cSb

The electrical resistivity of ${\mathrm{Tb}}_c{\mathrm{Y}}_{1-c}\mathrm{Sb}$ has been investigated as a function of temperature and Tb concentration in order to study the competing effects of the crystal field and the two-ion exchange interaction on the scattering of conduction electrons. The methods of growing and analyzing the crystals are outlined and the experimental technique of measuring the electrical resistivity is accounted for. A theoretical description of the scattering of conduction electrons from magnetic excitations is developed within a spherical model for the electronic energy bands. The resistivity is calculated using the random-phase approximation for the excitations of the ${\mathrm{Tb}}_c{\mathrm{Y}}_{1-c}\mathrm{Sb}$ system, both in the paramagnetic and the antiferromagnetically ordered phase. Satisfactory agreement with the experimental results is obtained for the entire range of concentration $c$ by use of only one value for each of the two adjustable parameters, the Fermi momentum and the electron-ion exchange constant.