A new three-dimensional subsulfide Ir₂In₈S with Dirac semimetal behavior

January 31, 2020

In a study published in the Journal of the American Chemical Society, researchers discovered a semimetal with a novel tetragonal structure, offering a new family of material systems to advance the field of topological materials.

(a) Crystal structure of Ir₂In₈S, containing IrIn₈ polyhedra with S anions in channels along the c axis. (b) Band structure with zoom-in on the two unique Dirac crossings near the Fermi level. (c) In Flux grown single crystal of Ir₂In₈S, highlighting the facile crystal growth from liquid indium. (d) Shubnikov-de Haas oscillations of Ir₂In₈S, giving insight into the Fermi surface and its topological behavior.

Scientific Achievement

We discovered a new three dimensional subsulfide Ir₂In₈S that has metal-metal and metal-chalcogenide bonding in the same compound. Ir₂In₈S is a Dirac semimetal candidate with two symmetry-protected crossings near the Fermi level.

Significance and Impact

Currently available Dirac semimetal candidate materials are limited in their structural diversity, with most belonging to a handful of the same structure types. Ir₂In₈S crystallizes in a new tetragonal structure type, offering a new material system to advance the field of topological materials.

Research Details

Indium metal flux stabilizes this novel subchalcogenide.
Ir₂In₈S has high electron mobility (~10000 cm²/Vs at 1.8 K) and large, anisotropic angular magnetoresistance with a maximum of ~6000%.
Shubnikov-de Haas oscillations suggest topological character.

DOI: 10.1021/jacs.9b10147

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