Magnetic excitations in tetragonal HoCr2Si2

Magnetic excitations in tetragonal HoCr2Si2 have been measured by neutron s pectroscopy. The temperature and Q dependence of the excitations measured a t 8 K confirm that they can be attributed to crystal field (CF) dipolar tra nsitions experienced by the Ho ion. The analysis of the neutron spectroscop y data for HoCr2Si2 is simplified by the fact that the CF coefficients have already been determined for the series RX2Si2 (R=rare earth, X=Cu, Ni) by neutron spectroscopy. In addition, electronic band structure calculations a nd experimental determinations of the electric field gradient for numerous compounds of the type RT2Si2 (T=Cr, Cu, Ni) show that the first-order CF co efficient, A(2)(0), changes sign when passing from the series RX2Si2 (X=Cr, Ni) to RCu2Si2. In the light of this information, the available neutron sp ectroscopy data for HoCr2Si2 are presented and discussed. (C) 2000 American Institute of Physics. [S0021-8979(00)52708-X].