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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ba4Ir3O10 by Materials Project

Ba4Ir3O10 is Orthorhombic Perovskite-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.62–3.06 Å. In the second Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.69–3.13 Å. There are two inequivalent Ir4+ sites. In the first Ir4+ site, Ir4+ is bonded to six O2- atoms to form face-sharing IrO6 octahedra. There are four shorter (2.06 Å) and two longer (2.07 Å) Ir–O bond lengths. In the second Ir4+ site, Ir4+ is bonded to six O2- atoms to form a mixture of corner and face-sharing IrO6 octahedra. The corner-sharing octahedral tilt angles are 27°. There are a spread of Ir–O bond distances ranging from 1.98–2.15 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+ and two equivalent Ir4+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to four Ba2+ and one Ir4+ atom. In the third O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+ and two Ir4+ atoms. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+ and two Ir4+ atoms. In the fifth O2- site, O2- is bonded to four Ba2+ and two Ir4+ atoms to form a mixture of distorted corner and edge-sharing OBa4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–7°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba4Ir3O10 by Materials Project

Ba4Ir3O10 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.74–3.08 Å. In the second Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.60–3.00 Å. There are two inequivalent Ir4+ sites. In the first Ir4+ site, Ir4+ is bonded to six O2- atoms to form face-sharing IrO6 octahedra. There are two shorter (2.06 Å) and four longer (2.07 Å) Ir–O bond lengths. In the second Ir4+ site, Ir4+ is bonded to six O2- atoms to form a mixture of corner and face-sharing IrO6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are a spread of Ir–O bond distances ranging from 2.00–2.15 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four Ba2+ and one Ir4+ atom. In the second O2- site, O2- is bonded in a 6-coordinate geometry to four Ba2+ and two Ir4+ atoms. In the third O2- site, O2- is bonded to four Ba2+ and two Ir4+ atoms to form a mixture of distorted corner and edge-sharing OBa4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two equivalent Ir4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Quantum liquid from strange frustration in the trimer magnet Ba4Ir3O10

Abstract Quantum spin systems such as magnetic insulators usually show magnetic order, but such classical states can give way to quantum liquids with exotic entanglement through two known mechanisms of frustration: geometric frustration in lattices with triangle motifs, and spin-orbit-coupling frustration in the exactly solvable quantum liquid of Kitaev’s honeycomb lattice. Here we present the experimental observation of a new kind of frustrated quantum liquid arising in an unlikely place: the magnetic insulator Ba 4 Ir 3 O 10 where Ir 3 O 12 trimers form an unfrustrated square lattice. The crystal structure shows no apparent spin chains. Experimentally we find a quantum liquid state persisting down to 0.2 K that is stabilized by strong antiferromagnetic interaction with Curie–Weiss temperature ranging from −766 to −169 K due to magnetic anisotropy. The anisotropy-averaged frustration parameter is 2000, seldom seen in iridates. Heat capacity and thermal conductivity are both linear at low temperatures, a familiar feature in metals but here in an insulator pointing to an exotic quantum liquid state; a mere 2% Sr substitution for Ba produces long-range order at 130 K and destroys the linear-T features. Although the Ir 4+ (5d 5 ) ions in Ba 4 Ir 3 O 10 appear to form Ir 3 O 12 trimers of face-sharing IrO 6 octahedra, we propose that intra-trimer exchange is reduced and the lattice recombines into an array of coupled 1D chains with additional spins. An extreme limit of decoupled 1D chains can explain most but not all of the striking experimental observations, indicating that the inter-chain coupling plays an important role in the frustration mechanism leading to this quantum liquid.

36 MATERIALS SCIENCE↗