Magnetoresistance in paramagnetic heavy fermion metals

TL;DR

This paper presents a theoretical analysis of magnetic field effects on heavy fermion metals, revealing how magnetoresistance and spectral features evolve with field and temperature, and shows good agreement with experimental data in CeB$_6$.

Contribution

It introduces a non-perturbative local moment approach within dynamical mean field theory to study magnetic field effects on heavy fermion metals, highlighting the behavior of the Kondo resonance and lattice coherence scale.

Findings

Magnetoresistance is negative across all temperatures.

Kondo resonance splits proportionally to magnetic field.

Lattice coherence peak shifts to higher temperatures with increasing field.

Abstract

A theoretical study of magnetic field (h) effects on single-particle spectra and transport quantities of heavy fermion metals in the paramagnetic phase is carried out. We have employed a non-perturbative local moment approach (LMA) to the asymmetric periodic Anderson model within the dynamical mean field framework. The lattice coherence scale $\om_L$, which is proportional within the LMA to the spin-flip energy scale, and has been shown in earlier studies to be the energy scale at which crossover to single impurity physics occurs,increases monotonically with increasing magnetic field. The many body Kondo resonance in the density of states at the Fermi level splits into two with the splitting being proportional to the field itself. For h$\geq$ 0, we demonstrate adiabatic continuity from the strongly interacting case to a corresponding non-interacting limit, thus establishing Fermi liquid behaviour for heavy fermion metals in the presence of magnetic field. In the Kondo lattice regime, the theoretically computed magnetoresistance is found to be negative in the entire temperature range. We argue that such a result could be understood at $T\gtrsim \om_L$ by field-induced suppression of spin-flip scattering and at $T\lesssim \om_L$ through lattice coherence. The coherence peak in the heavy fermion resistivity diminishes and moves to higher temperatures with increasing field. Direct comparison of the theoretical results to the field dependent resistivity measurements in CeB$_6$ yields good agreement.