Regensburg 2019 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 16: Methods in Computational Materials Modelling (methodological aspects, numerics)

MM 16.3: Talk

Tuesday, April 2, 2019, 10:45–11:00, H45

Hysteretic phase transitions of IrTe2: a unified picture from ab initio approaches — •Gabriele Saleh and Sergey Artyukhin — Istituto Italiano di Tecnologia, Via Morego 30, Genova 16163 Italy

A number of metal dichalcogenides are promising candidates for cutting-edge applications [1]. IrTe2 displays peculiar temperature-induced phase transitions to phases with Ir-Ir dimers [2] that can be tuned by doping and triggered by photoexcitation [3]. These transitions display hysteresis and they are accompanied by a change in the physical properties of the material, thus opening possibilities for technological applications. The various phases differ by the length of certain Ir-Ir and Te-Te bonds, that change up to 25% [3]. While a wealth of experimental results exist, the atomic-level understanding of transitions in IrTe2 is still poor. Here we present an in-depth computational investigation of the electronic structure and lattice dynamics of IrTe2. We demonstrate, through the combined use of several chemical bonding analysis approaches, that the electronic stability of low-T phases is determined by the formation of Ir2Te2 4-centre bonds. The high-T phase, instead, is stabilized by the higher entropic contribution of its phonons. We rationalize the observed hysteresis by analyzing the energetics of phase transitions through the Nudged Elastic Bands method. Finally, we present our preliminary results on the effect of doping on both the band structures and the phonon spectra of the IrTe2 phases. REFERENCES: [1] C. Tan et al. , Adv. Mater., 29(37), 1701392 (2017). [2] Q. Li et al. , Nat. Comm., 5, 5358 (2014). [3] S. I. Ideta et al. , Sci. Adv., 4(7), eaar3867 (2018).