Crystalline Electric Field Excitations in the Heavy Fermion Superconductor CeCoIn_5

TL;DR

This study uses inelastic neutron scattering to determine the crystalline electric field energy levels in the heavy fermion superconductor CeCoIn_5, revealing specific excitation energies and a detailed energy level scheme.

Contribution

It provides the first detailed CEF energy level scheme for CeCoIn_5 based on experimental INS data and CEF model fitting, advancing understanding of its electronic structure.

Findings

Observed CEF excitations at 8 meV and 27 meV.

Determined CEF parameters B^0_2, B^0_4, |B^4_4|.

Established the energy level scheme with specific wavefunctions.

Abstract

The crystalline electric field (CEF) energy level scheme of the heavy fermion superconductor CeCoIn_5 has been determined by means of inelastic neutron scattering (INS). Peaks observed in the INS spectra at 8 meV and 27 meV with incident neutron energies between E_i=30-60 meV and at a temperature T = 10 K correspond to transitions from the ground state to the two excited states, respectively. The wavevector and temperature dependence of these peaks are consistent with CEF excitations. Fits of the data to a CEF model yield the CEF parameters B^0_2=-0.80 meV, B^0_4=0.059 meV, and |B^4_4|= 0.137 meV corresponding to an energy level scheme: Gamma_7^(1) (0)[=0.487|+/-5/2> - 0.873|-/+3/2>], Gamma_7^(2) (8.6 meV, 100 K), and Gamma_6 (24.4 meV, 283 K).