Ferroic Coupling in Layered Perovskites from First Principles

Antiferrodistortive SrTiO$_3$ can be driven ferroelectric with a modest amount of biaxial strain. The n = 1 Ruddlesden-Popper remains paraelectric and undistorted for the same strain state. Elucidating the manner in which ferroic instabilities emerge as the number of perovskite blocks, n, increases is a fundamentally interesting challenge in its own right, yet a proper understanding could open new avenues in materials design. Combining first-principles calculations and symmetry arguments, we study the effect of strain (or pressure) and dimensionality on ferroic coupling in the layered Sr-Ti-O perovskites.