Angle-resolved photoemission study of dispersive and narrow-band5fstates in UAsSe

Abstract

Single crystals of ferromagnetic UAsSe have been investigated by angle-resolved photoemission spectroscopy (ARPES) in the photon energy range between $20\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ and $110\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$. Electron kinetic energy intensities are collected as a function of angle and mapped onto the materials reciprocal space. Energy-band mapping has been carried out both for a several-eV-wide energy interval as well as for a narrow energy interval of less than $1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ from the Fermi energy. The main features of the deduced energy bands can be explained by band-structure calculations. In the interval close to the Fermi energy, the very high energy and momentum resolution allows the observation of a narrow, yet dispersive photoemission peak mainly of $5f$ character situated within $50\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ of the Fermi energy. The Lorentzian linewidth was found to be about $35\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ with a dispersion of $30\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ along the $\ensuremath{\Gamma}$ to $Z$ direction and $40\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$ dispersion along the $\ensuremath{\Gamma}$ to $X$ direction in the Brillouin zone. We have also found broader (linewidth about $70\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$), hybridized $f$-character bands with a conventional dispersion of about $1\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ along the $\ensuremath{\Gamma}$ to $X$ and the $Z$ to $R$ directions in the Brillouin zone. An intriguing electronic structure emerges for UAsSe in which both relatively dispersive and narrow $5f$ bands are present. The occurrence of $5f$-band dispersions stipulates that the electronic structure of UAsSe requires lattice periodicity to be taken into account.