Experimental Band Structure of Pb(Zr,Ti)O : Mechanism of Ferroelectric Stabilization.

Pb(Zr,Ti)O (PZT) is the most common ferroelectric (FE) material widely used in solid-state technology. Despite intense studies of PZT over decades, its intrinsic band structure, electron energy depending on 3D momentum k, is still unknown. Here, Pb(Zr Ti )O using soft-X-ray angle-resolved photoelectron spectroscopy (ARPES) is explored.

Robust Electronic Structure of Manganite-Buffered Oxide Interfaces with Extreme Mobility Enhancement.

The electronic structure as well as the mechanism underlying the high-mobility two-dimensional electron gases (2DEGs) at complex oxide interfaces remain elusive. Herein, using soft X-ray angle-resolved photoemission spectroscopy (ARPES), we present the band dispersion of metallic states at buffered LaAlO/SrTiO (LAO/STO) heterointerfaces where a single-unit-cell LaMnO (LMO) spacer not only enhances the electron mobility but also renders the electronic structure robust toward X-ray radiation. By tracing the evolution of band dispersion, orbital occupation, and electron-phonon interaction of the interfacial 2DEG, we find unambiguous evidence that the insertion of the LMO buffer strongly suppresses both the formation of oxygen vacancies as well as the electron-phonon interaction on the STO side.

Band-Order Anomaly at the γ-AlO/SrTiO Interface Drives the Electron-Mobility Boost.

The rich functionalities of transition-metal oxides and their interfaces bear an enormous technological potential. Its realization in practical devices requires, however, a significant improvement of yet relatively low electron mobility in oxide materials. Recently, a mobility boost of about 2 orders of magnitude has been demonstrated at the spinel-perovskite γ-AlO/SrTiO interface compared to the paradigm perovskite-perovskite LaAlO/SrTiO interface.

Electronic Structure of a Graphene-like Artificial Crystal of NdNiO.

Artificial complex-oxide heterostructures containing ultrathin buried layers grown along the pseudocubic [111] direction have been predicted to host a plethora of exotic quantum states arising from the graphene-like lattice geometry and the interplay between strong electronic correlations and band topology. To date, however, electronic-structural investigations of such atomic layers remain an immense challenge due to the shortcomings of conventional surface-sensitive probes with typical information depths of a few angstroms. Here, we use a combination of bulk-sensitive soft X-ray angle-resolved photoelectron spectroscopy (SX-ARPES), hard X-ray photoelectron spectroscopy (HAXPES), and state-of-the-art first-principles calculations to demonstrate a direct and robust method for extracting momentum-resolved and angle-integrated valence-band electronic structure of an ultrathin buckled graphene-like layer of NdNiO confined between two 4-unit cell-thick layers of insulating LaAlO.

Orbital Ordering of the Mobile and Localized Electrons at Oxygen-Deficient LaAlO/SrTiO Interfaces.

Interfacing different transition-metal oxides opens a route to functionalizing their rich interplay of electron, spin, orbital, and lattice degrees of freedom for electronic and spintronic devices. Electronic and magnetic properties of SrTiO-based interfaces hosting a mobile two-dimensional electron system (2DES) are strongly influenced by oxygen vacancies, which form an electronic dichotomy, where strongly correlated localized electrons in the in-gap states (IGSs) coexist with noncorrelated delocalized 2DES. Here, we use resonant soft-X-ray photoelectron spectroscopy to prove the e character of the IGSs, as opposed to the t character of the 2DES in the paradigmatic LaAlO/SrTiO interface.

Large positive linear magnetoresistance in the two-dimensional t electron gas at the EuO/SrTiO interface.

The development of novel nano-oxide spintronic devices would benefit greatly from interfacing with emergent phenomena at oxide interfaces. In this paper, we integrate highly spin-split ferromagnetic semiconductor EuO onto perovskite SrTiO (001). A careful deposition of Eu metal by molecular beam epitaxy results in EuO growth via oxygen out-diffusion from SrTiO.

Spectro-microscopic photoemission evidence of charge uncompensated areas in Pb(Zr,Ti)O3(001) layers.

Photoelectron spectroscopy studies of (001) oriented PbTi0.8Zr0.2O3 (PZT) single crystal layers with submicron resolution revealed areas with different Pb 5d binding energies, attributed to the different charge and polarization states of the film surface.