First-principles study of two-dimensional electron and hole gases at the head-to-head and tail-to-tail 180${}^{\circ }$ domain walls in PbTiO${}_3$ ferroelectric thin films

Abstract

We study from first-principles the structural and electronic properties of head-to-head (HH) and tail-to-tail (TT) 180${}^{\circ }$ domain walls in isolated free-standing PbTiO${}_3$ slabs. For sufficiently thick domains ($n$ = 16 unit cells of PbTiO${}_3$), a transfer of charge from the free surfaces to the domain walls to form localized electron (in the HH) and hole (in the TT) gases in order to screen the bound polarization charges is observed. The electrostatic driving force behind this electronic reconstruction is clearly visible from the perfect match between the smoothed free charge densities and the bound charge distribution, computed from a finite difference of the polarization profile obtained after the relaxation of the lattice degrees of freedom. The domain wall widths, of around six unit cells, are larger than in the conventional 180${}^{\circ }$ neutral configurations. Since no oxygen vacancies, defects or dopant atoms are introduced in our simulations, all the previous physical quantities are the intrinsic limits of the system. Our results support the existence of an extra source of charge at the domains walls to explain the enhancement of the conductivity observed in some domains walls of prototypical, insulating in bulk, perovskite oxides.

arXiv comment8 pages, 5 figures

References in corpus (20)

• The SIESTA method for ab initio order-N materials simulation
• Efficient index handling of multidimensional periodic boundary conditions
• Numerical atomic orbitals for linear scaling
• Linear-scaling ab-initio calculations for large and complex systems
• Ab initio study of ferroelectric domain walls in PbTiO3
• Conduction through 71o domain walls in BiFeO3 thin films
• Conduction at domain walls in insulating Pb(Zr${}_{0.2}$Ti${}_{0.8}$)O${}_3$ thin films
• Theory of PbTiO3, BaTiO3, and SrTiO3 Surfaces
• "Head-to-head" and "tail-to-tail" 180-degree domain walls in an isolated ferroelectric
• Second-principles method including electron and lattice degrees of freedom
• Band alignment at metal/ferroelectric interfaces: insights and artifacts from first principles
• First-principles modeling of electrostatically doped perovskite systems
• First-principles calculation of the band offset at BaO/BaTiO${}_3$ and SrO/SrTiO${}_3$ interfaces
• Nanoscale Smoothing and the Analysis of Interfacial Charge and Dipolar Densities
• Berry-phase theory of polar discontinuities at oxide-oxide interfaces
• Theory of hypothetical ferroelectric superlattices incorporating head-to-head and tail-to-tail 180${}^{\circ }$ domain walls
• Two-dimensional electron gas at the PbTiO${}_3$/SrTiO${}_3$ interface: an ab initio study
• Model of two-dimensional electron gas formation at ferroelectric interfaces
• Origin of sawtooth domain walls in ferroelectrics
• Lattice screening of the polar catastrophe and hidden in-plane polarization in KNbO${}_3$/BaTiO${}_3$ interfaces

Cited by in corpus (4)

• Oxygen vacancies nucleate charged domain walls in ferroelectrics
• Parameter-free prediction of phase transition in PbTiO3 through combination of quantum mechanics and statistical mechanics
• Zig-zag charged domain walls in ferroelectric PbTiO${}_3$
• Predicting phase transitions in PbTiO${}_3$ using zentropy through quasiharmonic phonon calculations