Cornell, Brennan

In electron-doped ferroelectrics, the free electrons can become concentrated along the domain walls which act like a conducting surface. We consider the impact of free electrons occupying the t2g orbitals on the domain walls of an electron-doped perovskite ferroelectric. We build an analytical model based on Landau-Ginzburg-Devonshire theory, and a trio of tight-binding Hamiltonians for free electrons. We self-consistently solve for the polarization, potential, and electron density using a finite-difference approximation. We find that the ferroelectric is effectively charge neutral. The free electrons are attracted to the positively-charged domain wall, leaving it with a small residual charge. As the electron density increases, the domain walls tilt to form zig-zag domain walls. Orbital selectivity of the t2g orbitals depends on the relative orientations of the orbital plane and the domain wall. This property influences the rate at which the domain wall tilts as a function of the electron density.

Author Keywords: Charged Domain Wall, Domain Wall, Ferroelectric, Landau-Ginzburg, Perovskite, Strontium Titanate