Correlated Oxide Dirac Semimetal in the Extreme Quantum Limit

TL;DR

This paper reports on strain-engineered SrNbO3 thin films that exhibit topological Dirac electrons with ultra-high mobility, small effective mass, and fractional Landau level occupation, advancing the understanding of correlated topological quantum materials.

Contribution

It demonstrates how strain-induced symmetry changes in SrNbO3 create a topological band structure with correlated Dirac electrons and quantum limit phenomena.

Findings

Strained SrNbO3 shows ultra-high mobility (100,000 cm2/Vs).

Observation of fractional Landau level occupation.

Giant effective mass enhancement in strained films.

Abstract

Quantum materials (QMs) with strong correlation and non-trivial topology are indispensable to next-generation information and computing technologies. Exploitation of topological band structure is an ideal starting point to realize correlated topological QMs. Herein, we report that strain-induced symmetry modification in correlated oxide SrNbO3 thin films creates an emerging topological band structure. Dirac electrons in strained SrNbO3 films reveal ultra-high mobility (100,000 cm2/Vs), exceptionally small effective mass (0.04me), and non-zero Berry phase. More importantly, strained SrNbO3 films reach the extreme quantum limit, exhibiting a sign of fractional occupation of Landau levels and giant mass enhancement. Our results suggest that symmetry-modified SrNbO3 is a rare example of a correlated topological QM, in which strong correlation of Dirac electrons leads to the realization of fractional occupation of Landau levels.