Regensburg 2025 – scientific programme

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MA: Fachverband Magnetismus

MA 13: Altermagnets II

MA 13.10: Talk

Tuesday, March 18, 2025, 12:00–12:15, H20

Growth and properties of sputter-deposited altermagnetic RuO₂ thin films — •Maik Gaerner, Martin Wortmann, Judith Bünte, Inga Ennen, Andreas Hütten, Jan Schmalhorst, Timo Kuschel, and Günter Reiss — Bielefeld University, Germany

Altermagnetic materials exhibit time-reversal symmetry breaking and non-relativistic, anisotropic spin splitting in their bandstructure. RuO₂ is widely regarded as such an altermagnetic material, since e.g. spin-torque generation in RuO₂ has been observed [1]. However, muon spin rotation experiments [2] and density functional theory calculations [3] hint at the fragility of the magnetic order in RuO₂.

Here, we report on the growth and characterisation of RuO₂ thin films, deposited on MgF₂-, TiO₂- and MgO-substrates using reactive magnetron sputtering. In contrast to MgF₂-substrates, the lattice mismatch between the commonly used TiO₂-substrates and RuO₂ induces a significant strain on the RuO₂ which can enhance the density of states near the Fermi level [4]. We compare the crystallographic and electronic transport properties of the RuO₂ films, deposited at varying growth conditions and on the different substrates, with regard to the detection of the altermagnetic phase.
[1] Bose et al., Nat. Electron. 5, 267 (2022)

[2] Keßler et al., npj Spintronics 2, 50 (2024)

[3] Smolyanyuk et al., Phys. Rev. B 109, 134424 (2024)

[4] Ruf et al., Nat Commun 12, 59 (2021)

Keywords: Altermagnetism; Altermagnet; RuO2; Ruthenium dioxide; Magnetron Sputtering