Crystalline electric field in the thulium monochalcogenides

Inelastic neutron scattering experiments have been carried out to measure the magnetic response of the thulium monochalcogenides. From the excitation spectra observed for trivalent TmS and Tmsub(0.87)Se as well as for divalent TmTe the authors have determined the crystalline electric field level scheme, whereas no crystal-field splittings were observed for intermediate valent Tmsub(0.99)Se. The results are correlated in terms of reduced crystalline electric field parameters which point to similar charge distributions among the thulium monochalcogenides. Considerable dispersion effects were detected for Tmsub(0.87)Se. The line broadening effects vary through the thulium monochalcogenide series and are most clearly seen in TmTe where both sharp and broad magnetic response coexist. (Auth.)