Dimensional-Crossover-Driven Metal-Insulator Transition inSrVO3Ultrathin Films

Abstract

We have investigated the changes occurring in the electronic structure of digitally controlled ${\mathrm{SrVO}}_3$ ultrathin films across the metal-insulator transition (MIT) by the film thickness using in situ photoemission spectroscopy. With decreasing film thickness, a pseudogap is formed at $E_F$ through spectral weight transfer from the coherent part to the incoherent part. The pseudogap finally evolves into an energy gap that is indicative of the MIT in a ${\mathrm{SrVO}}_3$ ultrathin film. The observed spectral behavior is reproduced by layer dynamical-mean-field-theory calculations, and it indicates that the observed MIT is caused by the reduction in the bandwidth due to the dimensional crossover.