Description
Flexoelectricity, describing the polarization response to a gradient of the strain, is a universal property of all insulators that has attracted considerable attention in the past few years. [1] In spite of its fundamental and practical interest, it has long resisted theoretical attempts at quantifying it with predictive accuracy in realistic materials. In this talk, I will introduce the methodological advances that have recently lifted this limitation in the context of first-principles electronic-structure theory. [2] I will discuss applications to perovskite-structure SrTiO3, either in the cubic [3] or ferroelastic tetragonal phase. [4] I will also emphasize the generality of these newly established theoretical tools, with interesting connections to the physics of orbital magnetism, natural optical activity and magnetoelectric couplings.

[1] M. Stengel and D. Vanderbilt, in "Flexoelectricity in Solids From Theory to Applications", edited by A. K. Tagantsev and P. V. Yudin (World Scientific Publishing Co., Singapore, 2016).
[2] Miquel Royo and Massimiliano Stengel, Phys. Rev. X 9, 021050 (2019)
[3] M. Stengel, Phys. Rev. B 90, 201112(R) (2014) [4] Andrea Schiaffino and Massimiliano Stengel, Phys. Rev. Lett. 119, 137601 (2018)
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