Electrostatic engineering of strained ferroelectric perovskites from first principles

Abstract

Design of novel artificial materials based on ferroelectric perovskites relies on the basic principles of electrostatic coupling and in-plane lattice matching. These rules state that the out-of-plane component of the electric displacement field and the in-plane components of the strain are preserved across a layered superlattice, provided that certain growth conditions are respected. Intense research is currently directed at optimizing materials functionalities based on these guidelines, often with remarkable success. Such principles, however, are of limited practical use unless one disposes of reliable data on how a given material behaves under arbitrary electrical and mechanical boundary conditions. Here we demonstrate, by focusing on the prototypical ferroelectrics PbTiO3 and BiFeO3 as testcases, how such information can be calculated from first principles in a systematic and efficient way. In particular, we construct a series of two-dimensional maps that describe the behavior of either compound (e.g. concerning the ferroelectric polarization and antiferrodistortive instabilities) at any conceivable choice of the in-plane lattice parameter, a, and out-of-plane electric displacement, D. In addition to being of immediate practical applicability to superlattice design, our results bring new insight into the complex interplay of competing degrees of freedom in perovskite materials, and reveal some notable instances where the behavior of these materials depart from what naively is expected.

First-principles bulk-layer model for dielectric and piezoelectric responses in superlattices

“…1 shows the electric-elastic constitutive relations for SrTiO 3 , BaTiO 3 , and PbTiO 3 computed for displacement fields ranging from D = 0 to just above the ground state polarization of PbTiO 3 ( P = 0.85 C/m 2 ). The ferroelectrics BaTiO 3 and PbTiO 3 display a characteristic double well in the energy and a non-monotonic behavior of the electric field with displacement field, consistent with the results for PbTiO 3 shown in [19,20]. SrTiO 3 displays its characteristically flat energy well and nonlinear evolution of electric field with displacement field [21], which, as we will discuss below, gives rise to very large dielectric and piezoelectric responses for superlattices with large SrTiO 3 fraction.…”

Strain engineering of oxide thin films for photocatalytic applications

“…For integrations within the Brillouin zone we employ Monkhorst-Pack k-point grids [29] with a density equivalent to that of 16 × 16 × 16 in the fluorite CeO 2 unit cell. Strained-bulk geometry relaxations are performed with a conjugate-gradient algorithm that allows for volume variations while imposing the structural constraints defining thin films (|a| = |b| and α = 90 • ) [30][31][32][33]. Periodic boundary conditions are applied along the three directions defined by the lattice vectors, so that possible surface effects are completely avoided in the simulations.…”

Revisiting the zero-temperature phase diagram of stoichiometric SrCoO3 with first-principles methods

“…Oxide perovskites with the general formula ABO 3 , in which A and B denote different cations, can undergo abrupt structural, magnetic, and electronic changes upon application of small external fields (e. g., electric, magnetic, and mechanical) and variation of temperature [1][2][3][4][5][6][7][8][9][10]. This singular reactivity converts oxide perovskites in excellent candidate materials for developing new information storage and energy conversion technologies.…”