Publication Type
Journal
Journal Name
Physical Review B
Publication Date
Page Number
094428
Volume
77
Issue
9
Abstract
We use neutron scattering to study the Pr$^{3+}$ crystalline
electric field (CEF) excitations in the filled skutterudite
PrOs$_4$As$_{12}$. By comparing the observed levels and their
strengths under neutron excitation with the theoretical spectrum and
neutron excitation intensities, we identify the Pr$^{3+}$ CEF
levels, and show that the ground state is a magnetic
$\Gamma_4^{(2)}$ triplet, and the excited states $\Gamma_1$,
$\Gamma_4^{(1)}$ and $\Gamma_{23}$ are at 0.4, 13 and 23~meV,
respectively. A comparison of the observed CEF levels in
PrOs$_4$As$_{12}$ with the heavy fermion superconductor
PrOs$_4$Sb$_{12}$ reveals the microscopic origin of the differences
in the ground states of these two filled skutterudites.
