Are there crystal field levels in UPd2Al3? We answer, THERE ARE

TL;DR

This paper provides evidence for the existence of crystal field levels in UPd2Al3, countering recent claims, and explains their role in the compound's magnetic and electronic properties using a detailed theoretical framework.

Contribution

The authors demonstrate the presence of crystal field levels in UPd2Al3 and develop a theoretical model that explains experimental observations within the 5f3 U3+ configuration.

Findings

Crystal field excitations match INS data

The model explains the 1.7 meV magnetic exciton

Reproduces heat capacity and magnetic moment data

Abstract

We claim that crystal field (CEF) levels exist in UPd2Al3 in contrary to a recent claim of Hiess et al. (cond-mat/0411041) and Bernhoeft et al. (cond-mat/0411042), that there is no experimental evidence for discrete crystal field levels in this superconducting heavy-fermion antiferromagnet. We claim that excitations revealed by Krimmel et al. (J. Phys.: Condens. Matter 8 (1996) 1677 in inelastic-neutron-scattering (INS) studies are i) crystal-field excitations described by us within ii) the 5f3 (U3+) configuration. Moreover, our 5f3 (U3+) scheme, presented in Physica B 276-278 (2000) 803 and in Czech. J. Phys. 54 (2004) D295, provides a clear physical explanation for the 1.7 meV excitation (magnetic exciton) as associated to the removal of the Kramers-doublet ground state degeneracy in the antiferromagnetic state. The crystal-field theory completed by strong intra-atomic correlations and intersite spin-dependent interactions to the Quantum Atomistic Solid State Theory (QUASST), offers the meV energy scale needed for description of magnetic and electronic properties of compounds containing open-shell 3d, 4f, 5f atoms. The derived set of CEF parameters for the U3+ state reproduces both the INS excitations, temperature dependence of the heat capacity, large uranium magnetic moment as well as its direction. PACS: 71.70.E, 75.10.D Keywords: Crystalline Electric Field, Heavy fermion, magnetism, UPd2Al3