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

TL;DR

This study investigates how the oxygen coordination number in single-layer La-based cuprates influences their electronic structure, revealing unique properties in T*-type cuprates that differ from traditional octahedral systems.

Contribution

It provides the first detailed ARPES analysis of T*-type cuprates with five-fold pyramidal oxygen coordination, highlighting their distinct electronic behavior and challenging existing empirical rules.

Findings

Transition from Mott insulator to metal with oxygen content variation

Breakdown of Luttinger sum rule in T*-SmLa$_{1-x}$Sr$_x$CuO$_4$

Empirical $T_c$ rule does not apply to T*-type cuprates

Abstract

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.