Superconductivity in the Orbital Degenerate Model for Heavy Fermion Systems

TL;DR

This paper investigates how orbital splitting energy influences the emergence of superconductivity and magnetism in heavy fermion compounds using an orbital degenerate Hubbard model and fluctuation exchange approximation.

Contribution

It introduces a theoretical framework showing the pivotal role of orbital splitting energy in controlling quantum phase transitions in heavy fermion systems.

Findings

Superconducting phase with d_{x^2-y^2} symmetry appears near antiferromagnetic phase.

Orbital splitting energy controls the transition between magnetic and superconducting states.

The theory explains experimental observations in CeTIn5 compounds.

Abstract

Magnetism and superconductivity of new heavy fermion compounds CeTIn$_5$ (T=Co, Rh and Ir) are investigated by applying fluctuation exchange approximation to an orbital degenerate Hubbard model. The superconducting phase with $d_{x^2-y^2}$-symmetry is found to appear next to the antiferromagnetic phase with increasing the orbital splitting energy. The present theory suggests that the orbital splitting energy plays a key role of controlling parameter for the quantum phase transitions in the heavy fermion system.