Observation of mirror-odd and mirror-even spin texture in ultrathin epitaxially strained RuO<sub>2</sub> films.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 42525773.
- Also identified by DOI 10.1126/sciadv.aec2917 and PMC identifier 13418741.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Recently, rutile ruthenium dioxide (RuO<sub>2</sub>) has attracted renewed interest due to expectations of prominent altermagnetic spin splitting. However, accumulating experimental evidence suggests that, in its bulk and thick-film forms, RuO<sub>2</sub> does not display any form of magnetic ordering. Despite this, the spin structure of RuO<sub>2</sub> remains largely unexplored in the ultrathin limit, where substrate-imposed epitaxial strain can be substantial. Here, we use spin-resolved angle-resolved photoemission spectroscopy, supported by ab initio calculations, to reveal the electronic structure of 2-nanometer-thick epitaxial RuO<sub>2</sub> heterostructures. We observe an unconventional spin texture characterized by the coexistence of mirror-even and mirror-odd momentum-dependent components. A comprehensive symmetry analysis rules out nonmagnetic origins of this spin texture. These findings suggest an emergent nonrelativistic spin structure enabled by epitaxial strain in the ultrathin limit, marking a distinct departure from the behavior of relaxed or bulk RuO<sub>2</sub>. Our work opens previously unexplored perspectives for exploring symmetry-breaking mechanisms and spin textures in oxide heterostructures.