Complete band-structure determination of the quasi-two-dimensional Fermi-liquid reference compound TiTe2.

Abstract

The electronic structure of the layered compound 1T-${\mathrm{TiTe}}_{2}$ has been studied in detail by high-resolution angle-resolved photoelectron spectroscopy (ARPES) and density-functional band calculations. The results confirm the semimetallic nature of this material as due to an overlap of Te 5p- and Ti 3d-like conduction bands. We find an overall good correspondence between experiment and theory, with all ARPES structures accounted for by the calculated band structure. Particular focus is applied to the bands near the Fermi level and to the Fermi-surface topology. Interesting behavior is observed for an essentially Ti 3${\mathit{d}}_{\mathit{Z}}^{2}$-derived conduction band, whose measured Fermi vector and qualitative shape are excellently reproduced by the calculation. However, the experimental energy dispersion of the Ti 3${\mathit{d}}_{{\mathit{z}}^{2}}$ ARPES peak appears to be considerably reduced with respect to band theory. From these results we obtain a picture of the electronic structure of 1T-${\mathrm{TiTe}}_{2}$ as that of a Fermi liquid with renormalized quasiparticle dispersions and a Fermi surface in accordance with Luttinger's sumrule. We show that the experimental Ti 3${\mathit{d}}_{{\mathit{z}}^{2}}$ emission is quasi-two-dimensional near the Fermi surface, which, together with its being remarkably unobscured, virtually free of any interference with other spectral structures or inelastic background, makes it an ideal object for ARPES line-shape studies on a Fermi-liquid system. \textcopyright{} 1996 The American Physical Society.