Gradual Disappearance of the Fermi Surface near the Metal-Insulator Transition in La${}_{1-x}$Sr${}_x$MnO${}_3$

We report the first observation of changes in the electronic structure of La${}_{1-x}$Sr${}_x$MnO${}_3$ (LSMO) across the filling-control metal-insulator (MI) transition by means of in situ angle-resolved photoemission spectroscopy (ARPES) of epitaxial thin films. The Fermi surface gradually disappears near the MI transition by transferring the spectral weight from the coherent band near the Fermi level ($E_F$) to the lower Hubbard band, whereas a pseudogap behavior also exists in the ARPES spectra in the close vicinity of $E_F$ for the metallic LSMO. These results indicate that the spectral weight transfer derived from strong electron-electron interaction dominates the gap formation in LSMO associated with the filling-control MI transition.