High-pressure neutron and X-ray diffraction study of TmSe

The monochalcogenide TmSe is the unique compound which shows i) a long-range magnetic order at low temperature, ii) a metal-insulator transition at T(N), and iii) a temperature dependent spin fluctuation energy. To investigate the origin of its unusual physical properties, we have carried out high-pressure neutron elastic and inelastic as well as X-ray diffraction measurements on stoichiometric TmSe (a=5.709 A) at ambient and low temperatures. The basic aim of this work was to change, by the application of pressure, parameters which play an important role in the physics of the intermediate valence state and follow through by measuring physical quantities which are influenced by them