Influence of oxygen-coordination number on the electronic structure of single-layer La-based cuprates

We present an angle-resolved photoemission spectroscopy study of the single-layer T*-type structured cuprate SmLa${}_{1-x}$Sr${}_x$CuO${}_4$ with unique five-fold pyramidal oxygen coordination. Upon varying oxygen content, T*-SmLa${}_{1-x}$Sr${}_x$CuO${}_4$ evolved from a Mott-insulating to a metallic state where the Luttinger sum rule breaks down under the assumption of a large hole-like Fermi surface. This is in contrast with the known doping evolution of the structural isomer La${}_{2-x}$Sr${}_x$CuO${}_4$ with six-fold octahedral coordination. In addition, quantitatively characterized Fermi surface suggests that the empirical $T_{\mathrm{c}}$ rule for octahedral oxygen-coordination systems does not apply to T*-SmLa${}_{1-x}$Sr${}_x$CuO${}_4$. The present results highlight unique properties of the T*-type cuprates possibly rooted in its oxygen coordination, and necessitate thorough investigation with careful evaluation of disorder effects.