Analysis of the crystal electric field parameters of YbNi4P2

Abstract

The crystal electric field (CEF) scheme of YbNi _4 P _2 is determined, based on experimental data from inelastic neutron scattering, heat capacity, susceptibility and NMR measurements. Despite the tetragonal crystal structure, 9 parameters are needed to describe the crystal field in YbNi _4 P _2 due to the orthorhombic site symmetry of the Yb ion. A large basal plane anisotropy is detected by the local probe NMR. Our analysis yields CEF excitation energies of 8.5, 12.5 and roughly 30 meV and a ground state wave function that is dominated by the $5/2$ state. Furthermore, we present an analysis of the CEF scheme based on density functional theory calculations, which confirms the large basal plane anisotropy.

Keywords

• heavy-fermions
• crystal electric field
• density functional theory
• basal plane anisotropy