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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 8: (Multi)ferroic States: From Fundamentals to Applications (III)

KFM 8.4: Talk

Tuesday, March 18, 2025, 10:30–10:45, H9

Valence bond solid states in IrTe2 — •Sergey Artyukhin¹, Francesco Foggetti², and Daniel Khomskii³ — ¹Italian Institute of Technology — ²Uppsala University — ³University of Cologne

We study the phase diagram of IrTe2. This material manifests, below 280 K, a sequence of states where some Ir-Ir bonds shorten forming dimers, which results in a striped order. Ab-initio calculations suggest that the total energy is decreasing approximately linearly with the dimer fraction for the previously observed phases. The phonon density of states is shifted to higher frequencies, into the dimer-localized phonon bands. We describe the interactions between dimers using the force constant matrix from ab-initio calculations, and find features, similar to those driving striped orders in orthorhombic manganites. The strain texture is consistent with the observed striped orders. A simplified model, based on dimer energetics and phonon entropy, is formulated and the phase diagram of IrTe2 is obtained.

Keywords: valence bond solid; dimerized states