Electronic Structure of La2-xSrxCuO4 in the Vicinity of the Superconductor-Insulator Transition

We report on the result of angle-resolved photoemission (ARPES) study of La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) from an optimally doped superconductor ($x=0.15$) to an antiferromagnetic insulator ($x=0$). Near the superconductor-insulator transition (SIT) $x\sim 0.05$, spectral weight is transferred with hole doping between two coexisting components, suggesting a microscopic inhomogeneity of the doped-hole distribution. For the underdoped LSCO ($x\leq 0.12$), the dispersive band crossing the Fermi level becomes invisible in the $(0,0)-(\pi,\pi)$ direction unlike Bi$_2$Sr$_2$CaCu$_2$O$_{8+y}$. These observations may be reconciled with the evolution of holes in the insulator into fluctuating stripes in the superconductor.