Magnetoresistance in paramagnetic heavy fermion metals

Abstract

A theoretical study of magnetic field(h) effects on single-particle spectra and the transport quantities of heavy fermion metals inthe paramagnetic phase is carried out. We have employed a non-perturbativelocal moment approach (LMA) to the asymmetric periodic Anderson modelwithin the dynamical mean field framework. The lattice coherence scaleωL, which is proportional within the LMA to the spin-flip energy scale, and hasbeen shown in earlier studies to be the energy scale at which crossover tosingle-impurity physics occurs, increases monotonically with increasing magneticfield. The many body Kondo resonance in the density of states at the Fermi levelsplits into two, with the splitting being proportional to the field itself. Forh≥0, we demonstrate adiabatic continuity from the strongly interacting case to a correspondingnon-interacting limit, thus establishing Fermi liquid behaviour for heavy fermion metals inthe presence of a magnetic field. In the Kondo lattice regime, the theoreticallycomputed magnetoresistance is found to be negative in the entire temperaturerange. We argue that such a result could be understood at by field-induced suppression of spin-flip scattering and at through lattice coherence. The coherence peak in the heavy fermion resistivitydiminishes and moves to higher temperatures with increasing field. Direct comparisonof the theoretical results to the field dependent resistivity measurements inCeB6 yields good agreement.