High-resolution angle-resolved photoemission study of LaSb

Abstract

High-resolution angle-resolved photoemission spectroscopy (HR-ARPES) has been performed to study the electronic band structure of LaSb, which has no f electrons and is regarded as a nonmagnetic reference of CeSb and USb. HR-ARPES measurements near the Fermi level have established the existence of hole and electron pockets at the Brillouin-zone center and boundary, respectively, showing directly the semimetallic nature of LaSb. This supports the essential framework of the $p\ensuremath{-}f$ mixing model to explain the anomalous magnetic properties of CeSb based on the semimetallic band structure of the mother compound. ARPES spectra of LaSb have been calculated based on the linear-muffin-tin-orbital band structure to interpret the experimental result. The ``band structure'' obtained by ARPES is contributed to considerably by stationary lines with the zero group velocity ${(v}_{g}=\ensuremath{\partial}E/\ensuremath{\partial}k=0)$ midway between high-symmetry lines in the Brillouin zone. The overall feature of the band structure shows an excellent agreement between the experiment and the calculation while the Sb ${5p}_{3/2}$ bands that give two holelike Fermi surfaces at the \ensuremath{\Gamma} point are situated at higher binding energy by 0.3 eV in the calculation than in the experiment. Possible origins for the observed discrepancy are discussed.