K Hense

59Co NMR in ErCo3

Abstract NMR measurements of 59 Co in ferrimagnetic ErCo3 have been carried out between 4.2 and 120 K in external fields up to 7 T . The zero-field powder spectrum at 4.2 K shows three resolved lines at 23, 65, and 96 MHz . In a field along the c-axis the two lower frequencies decrease with increasing field at 10.01 MHz/T , while the upper one increases at the same rate. The temperature dependence of the upper line gives strong indication that the Co-moment of this sublattice decreases discontinuously at the transition temperature 100 K .

Lattice dynamics of YCu2

The lattice dynamics of the orthorhombic YCu2 compound has been studied by inelastic neutron scattering on a single crystal. An axially symmetric Born–von Karman model was applied to fit the neutron data. Ab initio calculations of the lattice dynamics at the Γ-point provided important additional information for the Born–von Karman fit procedure. The calculated phonon density of states was compared with time-of-flight experiments on powdered YCu2 sample material. The experimental studies were completed by Raman experiments and measurements of specific heat, thermal expansion, and compressibility.

Lattice dynamics and the interaction with the crystal electric field in NdCu2

The lattice dynamics of NdCu2 has been investigated with inelastic neutron scattering measurements. An uniaxial Born–von Karman model has been used to calculate the phonon dispersion relation. A verification of a phonon–crystal electric field (CEF) interaction was found from temperature dependent measurements of phonons and CEF excitations. The impact of the phonon–CEF interaction was found to be strongest at the Brillouin zone centre among the 7.5 meV Ag-phonon mode and the e4 CEF level. This has been verified with theoretical model calculations.