Ferroelectric instability under screened Coulomb interactions.

We explore the effect of charge carrier doping on ferroelectricity using density functional calculations and phenomenological modeling. By considering a prototypical ferroelectric material, BaTiO(3), we demonstrate that ferroelectric displacements are sustained up to the critical concentration of 0.11 electron per unit cell volume.

Ferroelectric control of the magnetocrystalline anisotropy of the Fe/BaTiO(3)(001) interface.

Density-functional calculations are employed to investigate the effect of ferroelectric polarization of BaTiO(3) on the magnetocrystalline anisotropy of the Fe /BaTiO(3)(001) interface. It is found that the interface magnetocrystalline anisotropy energy changes from 1.33 to 1.

Asymmetric magnetoresistance in an exchange bias Co/CoO bilayer.

Magnetoresistance (MR) measurements are carried out on a Co(8 nm)/CoO(3.5 nm) bilayer in the exchange bias (EB) state prepared by molecular beam epitaxy. With the applied magnetic field parallel to the current, the EB MR curves show an asymmetric behavior about the minimum, in contrast to the symmetric one for non-EB systems.

Prediction of a switchable two-dimensional electron gas at ferroelectric oxide interfaces.

The demonstration of a quasi-two-dimensional electron gas (2DEG) in LaAlO3/SrTiO3 heterostructures has stimulated intense research activity in recent years. The 2DEG has unique properties that are promising for applications in all-oxide electronic devices. For such applications it is desirable to have the ability to control 2DEG properties by external stimulus.

Interface effect on ferroelectricity at the nanoscale.

Interfaces play a critical role in nanoscale ferroelectricity. We perform a first-principles study of ultrathin KNbO(3) ferroelectric films placed between two metal electrodes, either SrRuO(3) or Pt. We show that bonding at the ferroelectric-metal interfaces imposes severe constraints on the displacement of atoms, destroying the bulk tetragonal soft mode.