Crystalline electric field effects in UPt2Si2 and URu2Si2

Abstract

It is shown that a simple crystalline electric field model is able to account for many of the magnetic properties of ${\mathrm{UPt}}_2$ ${\mathrm{Si}}_2$ and of ${\mathrm{URu}}_2$ ${\mathrm{Si}}_2$. For ${\mathrm{UPt}}_2$ ${\mathrm{Si}}_2$ (${\mathrm{URu}}_2$ ${\mathrm{Si}}_2$) a singlet-singlet-doublet-singlet (singlet-singlet-singlet-doublet) crystal-field level scheme is used to calculate the anisotropy, temperature dependence, and field dependence of the magnetization. For ${\mathrm{UPt}}_2$ ${\mathrm{Si}}_2$ a reasonable agreement is obtained with magnetic and neturon scattering results. For ${\mathrm{URu}}_2$ ${\mathrm{Si}}_2$ agreement with the magnetic measurement is fair, however, neutron scattering experiments give an estimate for the ordered moment of 0.03${\mu }_B$, which is much smaller than the calculated value.