We have investigated the magnetic excitations of ${\mathrm{URu}}_2{\mathrm{Si}}_2$ up to 800 meV using high energy inelastic neutron scattering. There is clear evidence of magnetic scattering in the energy range up to 200 meV. This scattering can be fitted to four broad peaks which we attribute to heavily damped crystal field excitations. We also observed the ${\mathrm{U}}^{4+}$ ${}^3{\overrightarrow{{\mathrm{H}}_4}}^3{\mathrm{F}}_2$ intermultiplet transition at 363 meV, which is a clear evidence of ${\mathrm{U}}^{4+}$ of ${\mathrm{URu}}_2{\mathrm{Si}}_2.$ We discuss our results with special attention to theoretical models proposed to explain the single ion physics of ${\mathrm{URu}}_2{\mathrm{Si}}_2,$ in particular the antiferromagnetic transition.

• Received 2 May 2002

DOI:https://doi.org/10.1103/PhysRevB.66.094502