Three-dimensional Fermi surface and electron-phonon coupling in semimetallic 1T - TiTe2 studied by angle-resolved photoemission spectroscopy

We present an investigation of the electronic structure of $1T\text{\ensuremath{-}}{\mathrm{TiTe}}₂$ single crystals using high-resolution angle-resolved photoemission spectroscopy utilizing tunable photon energy excitation. The typical semimetal-like electronic structure is observed and examined, where multiple hole pockets related to $\mathrm{Te}\phantom{\rule{0.28em}{0ex}}5p$ bands and one-electron pockets related to Ti $3d$ bands are populated by carriers. The obtained results reveal (i) a pronounced three-dimensional (3D) electronic band structure of $1T\text{\ensuremath{-}}{\mathrm{TiTe}}₂$ with typical semi-metallic features for both the Ti $3d$ and the $\mathrm{Te}\phantom{\rule{0.28em}{0ex}}5p$ states; (ii) multiple Fermi surface sheets and complex band structure; and (iii) an obvious kink in the dispersion at an energy of about 18 meV below the Fermi energy, which is an experimental observation of the kink structure in $1T\text{\ensuremath{-}}{\mathrm{TiTe}}₂$ single crystal. We find that this kink is induced by electron-phonon coupling in the material. These important and significant findings can help us to gain an in-depth understanding of the 3D electronic structure of semimetallic $1T\text{\ensuremath{-}}{\mathrm{TiTe}}₂$.