Magnetic field effects in the Anderson model of dilute magnetic alloys. III. Transport properties

An extension of previous studies is made on the magnetic field effects of the infinite-$U$ Anderson Hamiltonian. The magnetothermopower, the thermal magnetoresistivity, and the Lorenz number are calculated. We find that the thermopower decreases monotonically as a function of the applied field. In low fields, it varies linearly with the square of the impurity magnetization as well as with the negative electrical magnetoresistivity. In high fields, it follows a $\frac{1}{H}-\frac{1}{H_0}$ behavior. These features are in good qualitative agreement with the experiment of Berman and Kopp on Au-Fe alloys and with calculations based on the $s-d$ model. The field and temperature dependence of the negative thermal magnetoresistivity closely resemble those of the electrical one. A close parallelism is therefore established between the two quantities. The Lorenz number is found to be practically independent of the external magnetic field.