Antiferromagnetism atT>500Kin the layered hexagonal ruthenateSrRu2O6

Abstract

We report an experimental and computational study of magnetic and electronic properties of the layered Ru(V) oxide SrRu 2 O 6 (hexagonal, P3 ̅ 1m), which shows antiferromagnetic order with a Néel temperature of 563(2) K, among the highest for 4d oxides. Magnetic order occurs both within edge-shared octahedral sheets and between layers and is accompanied by anisotropic thermal expansivity that implies strong magnetoelastic coupling of Ru(V) centers.Electrical transport measurements using focused ion beam induced deposited contacts on a micron-scale crystallite as a function of temperature show p-type semiconductivity. The calculated electronic structure using hybrid density functional theory successfully accounts for the experimentally observed magnetic and electronic structure and Monte Carlo simulations reveals how strong intralayer as well as weaker interlayer interactions are a defining feature of the high temperature magnetic order in the material.

Spin waves and spin-state transitions in a ruthenate high-temperature antiferromagnet

“…While the nominal Ru valence of 5+ in the octahedral crystal field dictates three electrons in the 4d t 2g orbitals, a neutron powder diffraction study revealed a local magnetic moment of 1.4 µ B per Ru atom [14], which is significantly lower than 3 µ B expected for the high-spin S = 3/2 configuration. We synthesized hexagonal single crystals with typical diameter of ∼ 50 µm ( Fig.…”

“…Here we introduce a resonant inelastic x-ray scattering (RIXS) [10,11] technique capable of probing collective modes in microcrystals of 4d-electron materials. We present a comprehensive set of data on spin waves and spin-state transitions in the honeycomb antiferromagnet SrRu 2 O 6 [12], which possesses an unusually high Néel temperature [13][14][15][16][17][18]. The new RIXS method provides fresh insight into the unconventional magnetism of SrRu 2 O 6 , and enables momentum-resolved spectroscopy of a large class of 4d transition-metal compounds.…”

“…We have built an intermediate-energy RIXS spectrometer (IRIXS) with an analyzer designed for measurements at the L-adsorption edges of 4d metal compounds. Using this instrument, we obtained momentum-resolved spectra of spin waves and spin-state transitions from a microcrystal of SrRu 2 O 6 , a compound based on ruthenium-oxide honeycomb layers [12] whose extraordinar-ily high Néel temperature of 563 K [13,14] has recently inspired considerable theoretical work [15][16][17][18]. Models proposed to explain this observation include extended molecular orbitals on the hexagons of the honeycomb lattice [15], and a dichotomy of localized and itinerant valence electrons residing in different Ru orbitals [18].…”

“…These results establish IRIXS as an incisive probe of the low-energy electronic structure of a large variety of ruthenates and other 4d metal compounds. is insulating and exhibits G-type antiferromagnetism below T N = 563 K [13,14]. The Ru spins are oriented along the c-axis ( Fig.…”

Competition between spin-orbit coupling, magnetism, and dimerization in the honeycomb iridates: α−Li2IrO3 under pressure

“…However, the physics of this structural family is much richer and there are many more instabilities that interfere with the Kitaev interactions, in particular under pressure. Indeed, Li 2 RuO 3 is nonmagnetic and strongly dimerized at ambient pressure [13][14][15], while SrRu 2 O 6 is an ultra-high-temperature antiferromagnet [16,17], despite having the same planar geometry, and shows no bond disproportionation.Many factors control the competition between Kitaev physics, magnetism, and dimerization [18] in A 2 M O 3 honeycomb networks, such as the number of transition metal M d-electrons, the strength of spin-orbit coupling, the strength of correlation effects and Hund's rule coupling, or the ionic radii of the buffer element A. In this context it is particularly instructive to compare α-Li 2 IrO 3 with Li 2 RuO 3 , which contains the same buffer element (Li).…”