Dynamical Mean Field Studies of Infinite Layer Nickelates: Physics Results and Methodological Implications

Hanghui Chen,Jonathan Karp,Andrew J Millis,Frank Lechermann,Alexander Hampel

doi:10.3389/fphy.2022.835942

Abstract

This article summarizes recent work on the many-body (beyond density functional theory) electronic structure of layered rare-earth nickelates, both in the context of the materials themselves and in comparison to the high-temperature superconducting (high-Tc) layered copper-oxide compounds. It aims to outline the current state of our understanding of layered nickelates and to show how the analysis of these fascinating materials can shed light on fundamental questions in modern electronic structure theory. A prime focus is determining how the interacting physics defined over a wide energy range can be estimated and “downfolded” into a low energy theory that would describe the relevant degrees of freedom on the ∼0.5 eV scale and that could be solved to determine superconducting and spin and charge density wave phase boundaries, temperature dependent resistivities, and dynamical susceptibilities.

Highlights

The identification of a new class of superconductors is a momentous event
We present four levels of results: for orientation we show the density functional theory (DFT)-level electronic structure; we describe the basic manybody electronic structure following from the different DFT + dynamical mean field theory (DMFT) calculations and the approximate physical picture that results
The energy difference between Ni(3d) and O(2p) orbitals is larger in the nickelates than the cuprates, putting the nickelates farther from the charge transfer regime than are the cuprates

Summary

Introduction

The identification of a new class of superconductors is a momentous event. Ways in which the new superconductors are similar to or different from previously known materials can drive new insights into the microscopic origin of this fundamentally mysterious quantum many-body phenomenon. The discovery [1, 2] of superconductivity in layered copper-oxide materials sparked a revolution in condensed matter physics and materials science, because the transition temperatures were very high relative to other materials known at the time. Many aspects both of the superconductivity and of the non-superconducting (“normal state”) physics differed sharply from the predictions of conventional theory [3] in ways that made it obvious that interacting electron physics beyond mean field theory could have consequences of fundamental physics interest that approach (and in a few niche cases reach) commercial viability. Understanding the properties of the superconducting nickelates provides an immense scientific opportunity to sharpen our understanding of the relation between crystal structure and local chemistry on the one hand and important phenomena such as superconductivity on the other

Methods

Results

Conclusion