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Superconductivity induced by dimer breaking in layered Ir and Au ditellurides - Minoru Nohara - Mardi 21 mai 2019 à 11 h

INSP - Sorbonne Université - 4 place Jussieu - 75005 Paris - Barre 22-32, 2e étage, salle 201

Minoru Nohara - Okayama University, Japan

Abstract

Superconductivity at a relatively high transition temperature often emerges near structural instability that is characterized by pressure- or composition-induced structural transitions. Typical examples of this are Fe and Ni pnictides, Ir and Au tellurides, A15 compounds, and graphite intercalated compound CaC6. Among them, Ir and Au tellurides are interesting because their structural instabilities result from the breaking of molecular-like dimers of Ir and Te. In this talk, superconductivity and structural transition upon chemical substitution of IrTe2 and AuTe2 are reported.

IrTe2 exhibits a charge order transition at 270 K, characterized by a formation of Ir dimers. This state can be transformed into a superconducting state by chemical substitution or mechanical exfoliation. AuTe2 exhibits a structural transition that is characterized by the formation of Te dimers. This state can be suppressed by chemical substitution or hydrostatic pressure, and strong-coupling superconductivity emerges. These observations demonstrate that breaking molecular-like dimers in crystals are a promising route to developing superconductors.