Band Alignment, Built-In Potential, and the Absence of Conductivity at theLaCrO3/SrTiO3(001)Heterojunction

Abstract

Core-level and valence-band x-ray photoemission spectra measured for molecular-beam-epitaxy-grown LaCrO(3)/SrTiO(3)(001) yield band offsets and potential gradients within the LaCrO(3) sufficient to trigger an electronic reconstruction to alleviate the polarity mismatch. Yet, the interface is insulating. Based on first principles calculations, we attribute this unexpected result to interfacial cation mixing combined with charge redistribution within CrO(2) layers, enabled by low-lying d states within LaCrO(3), which suppresses an electronic reconstruction.

Magnetothermopower ofδ-dopedLaTiO3/SrTiO3interfaces in the Kondo regime

“…Here we report measurements of S(T, H) over a broad range of temperature (T) and magnetic field strength (H) in LTO/STO 2DEG system where a δ uc thick layer of LaCrO 3 (LCO) has been introduced at the interface. In agreement with the earlier studies [16,30,31], the pure LCO/STO interface remains insulating. However a conducting interface is realized when m uc layers of LTO are deposited over the δ uc LCO.…”

“…These presumably Kondo scatter electrons in pure LTO/STO system. In the case of δ-doped samples even Cr 3+ (S = 3/2) can Kondo scatter provided the antiferromagnetic order in LCO is broken close to LCO/STO interface due to non-zero intermixing as suggested by EELS and photoelectron spectroscopy measurements [16,30,31]. Uncompensated Cr 3+ spins can also result from incomplete antiferromagnetic order when odd number of LCO unit cells are deposited.…”

Band bending and alignment at the spinel/perovskiteγ−Al2O3/SrTiO3heterointerface

“…A built-in polar field and thus the presence of a potential gradient would have several consequences, which are in principle spectroscopically observable by HAXPES [15]. First, the O 2p-derived film valence band states will be pushed towards (and above) the chemical potential.…”

“…It provides detailed information of both the film and the substrate [12] and is in principle capable of detecting a built-in potential, as shown for other polar oxide heterostructures [15]. In this paper, we present a comprehensive analysis of the band arrangement at the GAO/STO heterointerface as inferred from HAXPES measurements.…”

Energetic, spatial, and momentum character of the electronic structure at a buried interface: The two-dimensional electron gas between two metal oxides

“…We suggest that similar multitechnique photoemission studies of such states at buried interfaces, combined with theory at the level we have employed, will be a very fruitful future approach for exploring and modifying the fascinating world of 2DEG and buried-interface physics, with applications in a wide variety of fields in materials science, physics, chemistry, and applied science. In fact, our above-and below-resonance SW technique has in more recent work been successfully applied to the system of LaCoO 3 and SrTiO 3 [61], two nonferroelectric materials which have been found to exhibit ferroelectric behavior at their interface [62]. As other examples looking ahead, we note the recent application of soft x-ray SW photoemission to the liquid-solid interface [13,63], with the above-and below-resonance methods described here promising to yield much more precise characterization of such interfaces in electrochemical cells [63] or gated devices involving a solid oxide and a liquid electrolyte [10].…”