The Fermi surface of PtCoO2 from quantum oscillations and electronic structure calculations

TL;DR

This study combines quantum oscillation measurements and electronic structure calculations to elucidate the Fermi surface and electronic correlations in the highly conductive layered oxide PtCoO2.

Contribution

It provides a detailed experimental and theoretical analysis of the Fermi surface of PtCoO2, highlighting the role of electronic correlations in its electronic structure.

Findings

Fermi surface consists of a single, warping cylinder with Pt character

Quantum oscillation frequencies reveal Fermi-surface warping and multiple close-lying frequencies

Electronic correlations in Co-O layers significantly influence the electronic structure

Abstract

The delafossite series of layered oxides include some of the highest conductivity metals ever discovered. Of these, PtCoO2, with a room temperature resistivity of 1.8 microOhmcm for in-plane transport, is the most conducting of all. The high conduction takes place in triangular lattice Pt layers, separated by layers of Co-O octahedra, and the electronic structure is determined by the interplay of the two types of layer. We present a detailed study of quantum oscillations in PtCoO2, at temperatures down to 35 mK and magnetic fields up to 30 T. As for PdCoO2 and PdRhO2, the Fermi surface consists of a single cylinder with mainly Pt character, and an effective mass close to the free electron value. Due to Fermi-surface warping, two close-lying high frequencies are observed. Additionally, a pronounced difference frequency appears. By analysing the detailed angular dependence of the quantum-oscillation frequencies, we establish the warping parameters of the Fermi surface. We compare these results to the predictions of first-principles electronic structure calculations including spin-orbit coupling on Pt and Co and on-site correlation U on Co, and hence demonstrate that electronic correlations in the Co-O layers play an important role in determining characteristic features of the electronic structure of PtCoO2.