Abstract
Bulk rutile RuO2 has long been considered a Pauli paramagnet. Here we report that RuO2 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 0.05μB 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 RuO2 unique among ruthenate compounds and among oxide materials in general.
| Original language | English |
|---|---|
| Article number | 077201 |
| Journal | Physical Review Letters |
| Volume | 118 |
| Issue number | 7 |
| DOIs | |
| State | Published - Feb 15 2017 |
Funding
We thank Veerle Keppens for the use of her laboratory equipment. The research was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division (T.B., P.C.S., O.D., Y.W., P.R.C.K., H.H.W.). Work by T.A.M. (response function calculation) was performed at the Center for Nanophase Materials Sciences, a DOE Office of Science user facility. H.D.Z. (crystal growth, XRD and low temperature susceptibility measurements) acknowledges support from NSF-DMR-1350002. M.R.K. (high temperature susceptibility measurements) acknowledges support from the Gordon and Betty Moore Foundations EPiQS Initiative through Grant No.GBMF4416. Research at ORNLs High Flux Isotope Reactor (H.B.C., M.M., S.X.C.) was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. DOE under Contract No.DE-AC02-05CH11231.