Correlated oxide Dirac semimetal in the extreme quantum limit.

Ok, Jong Mok; Mohanta, Narayan; Zhang, Jie; Yoon, Sangmoon; Okamoto, Satoshi; Choi, Eun Sang; Zhou, Hua; Briggeman, Megan et al. · Sci Adv · 2021

basic_science · Level V

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Abstract

Quantum materials (QMs) with strong correlation and nontrivial 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. Here, we report that strain-induced symmetry modification in correlated oxide SrNbO<sub>3</sub> thin films creates an emerging topological band structure. Dirac electrons in strained SrNbO<sub>3</sub> films reveal ultrahigh mobility (μ<sub>max</sub> ≈ 100,000 cm<sup>2</sup>/Vs), exceptionally small effective mass (<i>m</i>* ~ 0.04<i>m</i><sub>e</sub>), and nonzero Berry phase. Strained SrNbO<sub>3</sub> 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 SrNbO<sub>3</sub> is a rare example of correlated oxide Dirac semimetals, in which strong correlation of Dirac electrons leads to the realization of a novel correlated topological QM.