Quasiparticle Interactions for f$^2$-Impurity Anderson Model with Crystalline-Electric-Field: Numerical Renormalization Group Study

TL;DR

This study uses the Numerical Renormalization Group method to analyze quasiparticle interactions in an f$^2$-impurity Anderson model with crystalline-electric-field effects, focusing on implications for heavy fermion superconductivity.

Contribution

It provides new insights into interorbital quasiparticle interactions in f$^2$-based heavy fermions with crystalline-electric-field effects, relevant for understanding UPt$_3$ superconductivity.

Findings

Interorbital interactions exceed intraorbital ones in the studied model.

Results suggest interorbital interactions are crucial for UPt$_3$ superconductivity.

Contrasts with bare Coulomb interaction expectations.

Abstract

The aspect of the quasiparticle interaction of a local Fermi liquid, the impurity version of f$^2$-based heavy fermions, is studied by the Wilson numerical renormalization group method. In particular, the case of the f$^2$-singlet crystalline-electric-field ground state is investigated assuming the case of UPt$_3$ with the hexagonal symmetry. It is found that the interorbital interaction becomes larger than the intraorbital one in contrast to the case of the bare Coulomb interaction for the parameters relevant to UPt$_3$. This result offers us a basis to construct a microscopic theory of the superconductivity of UPt$_3$ where the interorbital interactions are expected to play important roles.