Neutron polarization analysis study of crystal field excitations in CePtSn

Abstract

We present the study of the Kondo antiferromagnet CePtSn, whose magnetic properties at T> T N can be explained by a strong anisotropy of the crystal-field (CF) potential on the Ce sites, which have an orthorhombic point-group symmetry. Applying a microscopic model with parameters deduced from magnetization and inelastic neutron scattering (INS) data, we predict a strong magnetic dipole moment parallel to the a-axis in the ground state. The dramatically increased count rate at the upgraded ILL three-axis spectrometer IN20 permits now to use the polarized beam even with a small single crystal sample (0.2 cm 3) to separate the CF signal from phonon background and to employ the XYZ polarization analysis to confirm directly this previously deduced anisotropy of the local CF Hamiltonian.