We have performed an angle-resolved photoemission spectroscopy study of ${\text{SrVO}}_3$ thin films. Utilizing thin films prepared in situ, with well-defined and atomically flat surfaces, contributions from surface states centered at $\sim -1.5\text{eV}$ were dramatically reduced, enabling us to study the bulklike $\text{V}3d$ states, including the incoherent part. A clear band dispersion is observed not only in the coherent part but also in the incoherent part and the spectral weight of the incoherent part is larger within the Fermi volume. These findings are particularly significant since the description of the so-called incoherent Hubbard band in ${\text{SrVO}}_3$ needs to include the nonlocal interaction between the atoms. These trends are well reproduced by dynamical mean-field theory calculations.

The concept ‘the interface is the device’ is embodied in a wide variety of interfacial electronic phenomena and associated applications in oxide materials, ranging from catalysts and clean energy systems to emerging multifunctional devices. Many device properties are defined by the band alignment, which is often influenced by interface dipoles. On the other hand, the ability to purposefully create and control interface dipoles is a relatively unexplored degree of freedom for perovskite oxides, which should be particularly effective for such ionic materials. Here we demonstrate tuning the band alignment in perovskite metal-semiconductor heterojunctions over a broad range of 1.7 eV. This is achieved by the insertion of positive or negative charges at the interface, and the resultant dipole formed by the induced screening charge. This approach can be broadly used in applications where decoupling the band alignment from the constituent work functions and electron affinities can enhance device functionality.

The correlated electronic structure of ${\mathrm{SrVO}}_3$ has been investigated by angle-resolved photoemission spectroscopy using in situ prepared thin films. Pronounced features of band renormalization have been observed: a sharp kink $\sim 60\mathrm{meV}$ below the Fermi level ($E_F$) and a broad so-called “high-energy kink” $\sim 0.3\mathrm{eV}$ below $E_F$ as in the high-$T_c$ cuprates, although ${\mathrm{SrVO}}_3$ does not show magnetic fluctuations. We have deduced the self-energy in a wide energy range by applying the Kramers-Kronig relation to the observed spectra. The obtained self-energy clearly shows a large energy scale of $\sim 0.7\mathrm{eV}$, which is attributed to electron-electron interaction and gives rise to the $\sim 0.3\mathrm{eV}$ kink in the band dispersion as well as the incoherent peak $\sim 1.5\mathrm{eV}$ below $E_F$. The present analysis enables us to obtain a consistent picture for both the incoherent spectra and the band renormalization.

The authors report on the band diagram for epitaxial Schottky junctions of ferromagnetic metallic oxides [half-metallic ferromagnet ${\mathrm{La}}_{0.6}{\mathrm{Sr}}_{0.4}\mathrm{Mn}{\mathrm{O}}_3$ (LSMO) and itinerant ferromagnet $\mathrm{Sr}\mathrm{Ru}{\mathrm{O}}_3$ (SRO)] on Nb-doped $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_3$ (Nb:STO) semiconductor substrates using in situ photoemission spectroscopy. The ideal Schottky barrier is formed in SRO/Nb:STO junctions with Schottky barrier height (SBH) of $1.2\pm 0.1\mathrm{eV}$ , while the measured SBH of LSMO/Nb:STO $(1.2\pm 0.1\mathrm{eV})$ is much larger than the prediction from the Schottky-Mott rule $(0.7\pm 0.1\mathrm{eV})$ . These results suggest that a certain interface dipole is formed at the LSMO/Nb:STO interface.

Using low-temperature electrical measurements, the interrelation between electron transport, magnetic properties, and ionic defect structure in complex oxide interface systems is investigated, focusing on ${\mathrm{NdGaO}}_3/{\mathrm{SrTiO}}_3$ (100) interfaces. Field-dependent Hall characteristics (2–300 K) are obtained for samples grown at various growth pressures. In addition to multiple electron transport, interfacial magnetism is tracked exploiting the anomalous Hall effect (AHE). These two properties both contribute to a nonlinearity in the field dependence of the Hall resistance, with multiple carrier conduction evident below 30 K and AHE at temperatures $\lesssim 10\mathrm{K}$. Considering these two sources of nonlinearity, we suggest a phenomenological model capturing the complex field dependence of the Hall characteristics in the low-temperature regime. Our model allows the extraction of the conventional transport parameters and a qualitative analysis of the magnetization. The electron mobility is found to decrease systematically with increasing growth pressure. This suggests dominant electron scattering by acceptor-type strontium vacancies incorporated during growth. The AHE scales with growth pressure. The most pronounced AHE is found at increased growth pressure and, thus, in the most defective, low-mobility samples, indicating a correlation between transport, magnetism, and cation defect concentration.

We have investigated the interfacial termination layer dependence of the Schottky barrier height (SBH) for heterojunctions between polar ${\text{La}}_{0.6}{\text{Sr}}_{0.4}{\text{MnO}}_3$ (LSMO) and nonpolar Nb-doped ${\text{SrTiO}}_3$ (Nb:STO). The SBH for $\text{LSMO}/{\text{TiO}}_2\text{-Nb}:\text{STO}$ is higher than the SBH predicted from the Schottky-Mott rule by 0.5 eV, indicating the formation of an interface dipole. In contrast, for LSMO/SrO-Nb:STO, the SBH is lower than that predicted from the Schottky-Mott rule by 0.4 eV. These results indicate that a change in the polarity of the polar LSMO overlayers results in inversion of the direction of the interface dipole. The modulation of SBH depending on the interfacial termination layer is reasonably explained by interfacial electronic reconstruction to prevent polar divergence.