Unconventional two-dimensional quantum oscillations in three-dimensional thick SrRuO$_3$ films

TL;DR

This study investigates quantum oscillations in thick SrRuO$_3$ films, revealing coexistence of two-dimensional surface Fermi arc states and providing insights into their origin related to Weyl points.

Contribution

It provides the first detailed analysis of quantum oscillations in thick SrRuO$_3$ films, linking them to surface Fermi arc states and clarifying their origin.

Findings

Quantum oscillations originate from two-dimensional surface states.

Two oscillation components with different effective masses were identified.

Surface Fermi arc states are involved in the observed oscillations.

Abstract

SrRuO$_3$ is a prototypical transition metal oxide which hosts rich physical properties including itinerant ferromagnetism, high conductivity, and intrinsic Hall effect originating in the Weyl points. Recently, high-quality SrRuO$_3$ films with residual resistivity ratios of more than 50 have been reported to exhibit quantum oscillations at low temperatures in spite of its strong electron correlation. While the origin of the oscillations has been discussed in relation to Weyl orbits based on the Weyl semimetal band structure, so far experimentally reported results are neither consistent with each other nor with theoretically expected behavior, leaving the origin of the oscillations in SrRuO$_3$ films still elusive. In this report, we have carefully evaluated the quantum oscillations observed in three-dimensional thick SrRuO$_3$ films with a high residual resistivity ratio of RRR = 82. We reveal the coexistence of two oscillation components both derived from two-dimensional electronic states and with slightly different masses, suggesting the involvement of the surface Fermi arc states formed between different Weyl point pairs.