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