Electronic nematicity in Sr<sub>2</sub>RuO<sub>4</sub>.

Wu, Jie; Nair, Hari P; Bollinger, Anthony T; He, Xi; Robinson, Ian; Schreiber, Nathaniel J; Shen, Kyle M; Schlom, Darrell G et al. · Proc Natl Acad Sci U S A · 2020

basic_science · Level V

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Abstract

We have measured the angle-resolved transverse resistivity (ARTR), a sensitive indicator of electronic anisotropy, in high-quality thin films of the unconventional superconductor Sr<sub>2</sub>RuO<sub>4</sub> grown on various substrates. The ARTR signal, heralding the electronic nematicity or a large nematic susceptibility, is present and substantial already at room temperature and grows by an order of magnitude upon cooling down to 4 K. In Sr<sub>2</sub>RuO<sub>4</sub> films deposited on tetragonal substrates the highest-conductivity direction does not coincide with any crystallographic axis. In films deposited on orthorhombic substrates it tends to align with the shorter axis; however, the magnitude of the anisotropy stays the same despite the large lattice distortion. These are strong indications of actual or incipient electronic nematicity in Sr<sub>2</sub>RuO<sub>4</sub>.