Gian G. Guzmán-Verri, Universidad de Costa Rica, San José, Costa Rica

Thursday June 22 at 2:00 pm (Paris time)

Room Holweck, building C, 1st floor

Tuning structural and electronic phase transitions in elastic media

In complex functional materials, the primary drivers of their phase transitions are instabilities of different nature such as magnetic, polar, charge or orbital. It is also well known that many of those transformations can be tuned by parameters such as ionic size in a chemical series, sometimes without causing significant changes to their local energy structure. In this talk, I want to argue that even when the transition is clearly driven by a local instability, strain mediated interactions between the primary degrees of freedom can produce enormous entropic contributions to the free energy that are usually ignored by conventional theories. I will illustrate this idea with a phenomenological theory in which the primary order parameter of the phase transition is coupled to elastic strains and strain gradients in three classes of materials, namely the colossal magnetoresistance manganites [1], the perovskite quantum paraelectrics [2], and the tellurides [3].

Work supported by the Vicerrectory for Research at the University of Costa Rica.

[1] G. G. Guzmán -Verri, R. T. Brierley, and P.B. Littlewood, Nature 576, 429 (2019).

[2] G. G. Guzmán -Verri, C. H. Liang, and P.B. Littlewood, arXiv : 2205.14171.

[3] S. Kimber et al., Nature Materials 22, 311 (2023).

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