Density functional study ofPbTiO3nanocapacitors with Pt and Au electrodes

Abstract

We present an ab initio density functional study of ferroelectricity in single-domain PbTiO 3 -based nanocapacitors. We used density functional theory with the recently introduced PBEsol generalized-gradient exchange-correlation functional, which we found to give accurate properties of bulk ferroelectric ͑FE͒ materials. Pt and Au electrodes are used in our study to gain a thorough understanding of the electrode-oxide interfaces, and the role of the interfacial chemical bonding and charge transfer in stabilizing the FE polar phase. We found that the FE properties of the thin films depend not only on the electrode and the FE material but also on the electrode-perovskite termination ͑TiO 2 vs PbO͒, exemplifying the key role of the interface in these systems. The critical thickness was found to be 24-28 Å. In addition, a Löwdin orbital analysis gives a detailed description of the distribution of charges in the system, and shows the importance of charge passivation by the electrodes in stabilizing the FE polar phase.

Stabilization of highly polarized PbTiO3nanoscale capacitors due to in-plane symmetry breaking at the interface

“…localized charge transfer at the interfaces; this effect is confined to the interface layers, and the bulk PTO layers remain insulating. This is in agreement with previous studies of the AO/Pt interfaces, 13,14,18,23,26 and it means that our system exhibits proper band alignment of the metal and oxide 30 . Also, supporting this conclusion, the cation displacements with respect to oxygen atoms in each layer (rumplings, Fig.…”

Doping-induced phase transitions in ferroelectric BaTiO3from first-principles calculations

“…64.32Å 3 ) in T phase BaTiO 3 , which agrees well with previous reports. 18,19 The effects of electron doping and dopant-induced lattice disorder were evaluated using different charge compensation models; namely, charge compensation with uniform background charges without the effects of lattice disorder and compensation with supercell models containing typical dopants such as Nb 5+ at Ti 4+ sites and V 2+ O . number of the grids.…”

Interfacial dead layer effects on current-voltage characteristics in asymmetric ferroelectric tunnel junctions

“…1, P iL and P iR are the polarization of the left and right interface, respectively, and P iL (P iR ) is assumed to be fixed [9]. From the first-principles calculations, it is found that the effects of the interfacial dead layer extend for only 1-2 atomic layers [15]. Therefore, the thickness of the interface layer is chosen as one unit cell in this paper, i.e., d iL =d iR =4Å.…”