UV and x-ray photoelectron spectra of valence band of LaB6

The total density of occupied states in the electronic structure of lanthanum hexaboride has been measured by use of high-resolution photoelectron spectroscopy combining far UV (Ne and He resonance lines) and x-ray excitation (monochromatized Al K α radiation). The investigation was performed with clean and stoichiometric surfaces from poly-crystalline bulk samples and thin films, both prepared in situ. The data give new insights into bonding, band structure and thermal stability of LaB6. The valence band (approximately 12eV wide) is characterized by three main bands located at about 2 eV, 5 eV and 10 eV with additional subsidiary structures. The data are compared with published results of soft x-ray studies and the energy, position and width of the experimental bands compared and interpreted with available band-structure calculations. (author)