Towards a Theory of the Anomalous Thermoelectric Effect in Magnetically Dilute Alloys

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Abstract
The low-temperature properties of alloys of the noble metals with low concentrations of transition metals show many anomalies, conspicuous among them relatively enormous thermoelectric powers and non-monotonic behavior of the resistivity with temperature. We investigate to what extent these anomalies might be explained by supposing the existence of spiraling magnetic polarizations of the electron gas, i.e., static spin-density waves. We discuss qualitatively how thermoelectric anomalies can arise, first in terms of an earlier theory which requires weak ferromagnetism in the noble metals and then in terms of the spin-density-wave hypothesis, an assumption of weak antiferromagnetism. We solve the Boltzmann equation, including inelastic scattering, for the two theories and display the thermoelectric powers and resistivities as functions of the temperature. We consider several different models of spin-density-wave system, one appropriate to electron-electron interactions proportional to delta functions in the separation, another an approximation to Coulombic interelectron forces, and finally a linear spin-density wave as the simplest case of a multiple spin-density-wave configuration. We find that the spin-density-wave hypothesis can explain the magnitudes of the thermoelectric anomalies. Further, we find nonmonotonic resistivity behavior. A comparison with experiments shows that our model is too simple to provide a detailed explanation of the anomalous thermoelectricity and that the nonmonotonic resistivity we find cannot be associated with that observed experimentally.