Pinball liquid phase from Hund's coupling in frustrated transition metal oxides

TL;DR

This paper investigates how Hund's coupling influences electronic phases in frustrated transition metal oxides, revealing a stable pinball liquid phase with unique charge and magnetic properties, relevant to materials like AgNiO2.

Contribution

It introduces a comprehensive phase diagram showing the emergence of a pinball liquid phase driven by Hund's coupling in a multiband Hubbard model.

Findings

Identification of a robust pinball liquid phase

Explanation of anomalous charge-ordered metallic state in AgNiO2

Discussion of relevance to other triangular transition metal oxides

Abstract

The interplay of non-local Coulomb repulsion and Hund's coupling in the d-orbital manifold in frustrated triangular lattices is analyzed by a mutliband extended Hubbard model. We find a rich phase diagram with several competing phases, including a robust pinball liquid phase, which is an unconventional metal characterized by threefold charge order, bad metallic behavior and the emergence of high spin local moments. Our results naturally explain the anomalous charge-ordered metallic state observed in the triangular layered compound AgNiO2. The potential relevance to other triangular transition metal oxides is discussed.