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arXiv · 1612.09589

Itinerant Antiferromagnetism in RuO$_{2}$

T. Berlijn·P. C. Snijders·O. Delaire·H. -D. Zhou·T. A. Maier·H. -B. Cao·S. -X. Chi·M. Matsuda·Y. Wang·M. R. Koehler·P. R. C. Kent·H. H. Weitering
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Abstract

Bulk rutile RuO$_2$ has long been considered a Pauli paramagnet. Here we report that RuO$_2$ exhibits a hitherto undetected lattice distortion below approximately 900 K. The distortion is accompanied by antiferromagnetic order up to at least 300 K with a small room temperature magnetic moment of approximately 0.05 $μ_B$ as evidenced by polarized neutron diffraction. Density functional theory plus $U$ (DFT+$U$) calculations indicate that antiferromagnetism is favored even for small values of the Hubbard $U$ of the order of 1 eV. The antiferromagnetism may be traced to a Fermi surface instability, lifting the band degeneracy imposed by the rutile crystal field. The combination of high Néel temperature and small itinerant moments make RuO$_2$ unique among ruthenate compounds and among oxide materials in general.

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T. Berlijn, P. C. Snijders, O. Delaire, H. -D. Zhou, T. A. Maier, H. -B. Cao, S. -X. Chi, M. Matsuda, Y. Wang, M. R. Koehler, P. R. C. Kent, H. H. Weitering. 2016-12-30. Itinerant Antiferromagnetism in RuO$_{2}$. https://doi.org/10.1103/physrevlett.118.077201

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