From high-$T_c$ to low-$T_c$: Multi-orbital effects in transition metal oxides

TL;DR

This paper investigates how multi-orbital effects influence superconductivity in transition metal oxides, explaining differences in critical temperatures between cuprates and nickelates through a minimal two-orbital model.

Contribution

It introduces a two-orbital $e_g$ model that captures key differences in superconducting tendencies of cuprates and nickelates based on orbital splitting and other parameters.

Findings

Orbital splitting significantly affects pairing propensities.

The model explains the variation in $T_c$ among different transition metal oxides.

Interactions and doping levels modulate superconducting instabilities.

Abstract

Despite the structural resemblance of certain cuprate and nickelate parent compounds there is a striking spread of $T_c$ among such transition metal oxide superconductors. We adopt a minimal two-orbital $e_g$ model which covers cuprates and nickelate heterostructures in different parametric limits, and analyse its superconducting instabilities. The joint consideration of interactions, doping, Fermiology, and in particular the $e_g$ orbital splitting allows us to explain the strongly differing pairing propensities in cuprate and nickelate superconductors.