  We have performed angle-resolved photoemission spectroscopy of Bi(111) thin
films grown on Si(111), and investigated the evolution of band structure with
temperature. We revealed an unexpectedly large temperature variation of the
energy dispersion for the Rashba-split surface state and the quantum-well
states, as seen in the highly momentum-dependent energy shift as large as 0.1
eV. A comparison of the band dispersion between experiment and first-principles
band-structure calculations suggests that the interlayer spacing at the topmost
Bi bilayer expands upon temperature increase. The present study provides a new
pathway for investigating the interplay between lattice and electronic states
through the temperature dependence of band structure.
