Hysteresis proves that the In/Si(111)(8×2)to(4×1)phase transition is first-order

Abstract

Indium on silicon (111) exhibits a Peierls-like phase transition from a $(4\ifmmode\times\else\texttimes\fi{}1)$ reconstructed high-temperature phase to a $(8\ifmmode\times\else\texttimes\fi{}2)$ reconstructed ground state. A controversial debate is going on what kind of phase transition it is: first- or second-order. We employed high-resolution low-energy electron diffraction under slow thermal heating and cooling cycles to follow the phase transition. A robust hysteresis of diffraction spot intensities with a width of 8.6 K has been observed, which is independent of the heating and cooling rate. This hysteresis directly proves the existence of an energy barrier at the phase transition temperature and thus the first-order behavior of this phase transition.