Route to tunable room temperature electric polarization in SrTiO₃–CoFe₂O₄ heterostructures

Abstract

We show reversible room temperature control of the Ti band structure in SrTiO3–CoFe2O4 heterostructures exploiting CoFe2O4 magnetostriction. Changes as a function of the applied magnetic field suggest the development of a net electric polarization.

Charge Transfer and Orbital Reconstruction at an Organic–Oxide Interface

“…Figure 4a shows the XAS acquired in S and P polarizations of 0.6 ML of TCNQ/STO and of pristine STO, with the corresponding XLD spectra shown in panels b and c. Upon molecular adsorption, the XLD signal in the region between 456.5 and 458.5 eV (corresponding to the Ti 2p 3/2 → 3d t 2g transition�highlighted by a red box in the figure) is reversed, as already observed in STO upon LAO coverage. 42 Multiplet calculations shown in panels b and c can qualitatively describe this behavior by breaking the cubic symmetry of the bulk and reversing the sign of D s from +20 meV in the annealed case 43,44 to −20 meV after deposition of TCNQ. The D s parameter in the calculations corresponds to the energy splitting between the in-plane and out-of-plane orbitals in the t 2g manifold, and its change of sign indicates an orbital reorganization at the STO surface upon molecular adsorption.…”