Emergent Interfacial Magnetism in Epitaxial RuO$_2$

Yudi Yang; Zhuang Qian; Shi Liu; Congjun Wu

Emergent Interfacial Magnetism in Epitaxial RuO$_2$

Materials Science 2026-07-17 v1

Authors: Yudi Yang , Zhuang Qian , Shi Liu , Congjun Wu

Abstract

The magnetic ground state of the altermagnet candidate RuO $_2$ remains controversial, with magnetic signatures observed mainly in epitaxial films. Here we show, using first-principles calculations, that magnetism in epitaxial RuO $_2$ can emerge as an interfacial boundary phase at TiO $_2$ /RuO $_2$ interfaces. While TiO $_2$ -induced epitaxial strain alone does not make (001)-oriented RuO $_2$ magnetic, explicit TiO $_2$ /RuO $_2$ interfaces stabilize sizable Ru moments confined to the first few Ru layers. Charge-density and orbital-resolved analyses reveal interfacial electronic reconstruction, and substrate doping provides a route to tune the induced moments. In symmetric TiO $_2$ /RuO $_2$ /TiO $_2$ heterostructures, the two magnetic interfaces couple through the metallic RuO $_2$ spacer, producing a thickness-dependent alternation between weak-ferromagnetic and compensated altermagnetic states. Our results identify interface engineering as a practical route to stabilize and control fragile magnetism in RuO $_2$ .

Keywords

RuO2 altermagnet interfacial magnetism first-principles calculations epitaxial strain heterostructures electronic reconstruction

Cite

@article{arxiv.2607.16093,
  title  = {Emergent Interfacial Magnetism in Epitaxial RuO$_2$},
  author = {Yudi Yang and Zhuang Qian and Shi Liu and Congjun Wu},
  journal= {arXiv preprint arXiv:2607.16093},
  year   = {2026}
}