Microscopic origin of the mobility enhancement at a spinel/perovskite oxide heterointerface revealed by photoemission spectroscopy

Abstract

The spinel/perovskite heterointerface $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$ hosts a two-dimensional electron system (2DES) with electron mobilities exceeding those in its all-perovskite counterpart LaAlO${}_3$/SrTiO${}_3$ by more than an order of magnitude despite the abundance of oxygen vacancies which act as electron donors as well as scattering sites. By means of resonant soft x-ray photoemission spectroscopy and \textit{ab initio} calculations we reveal the presence of a sharply localized type of oxygen vacancies at the very interface due to the local breaking of the perovskite symmetry. We explain the extraordinarily high mobilities by reduced scattering resulting from the preferential formation of interfacial oxygen vacancies and spatial separation of the resulting 2DES in deeper SrTiO${}_3$ layers. Our findings comply with transport studies and pave the way towards defect engineering at interfaces of oxides with different crystal structures.

Accepted as Rapid Communications in Physical Review B

References in corpus (7)

• A high-mobility two-dimensional electron gas at the heteroepitaxial spinel/perovskite complex oxide interface of γ-Al2O3/SrTiO3
• High mobility conduction at (110) and (111) LaAlO3/SrTiO3 interfaces
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• Intrinsic Mobility Limiting Mechanisms in Lanthanum-doped Strontium Titanate
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• Localized versus itinerant states created by multiple oxygen vacancies in SrTiO3
• Anomalous orbital structure in a spinel-perovskite interface $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$

Cited by in corpus (1)

• Magnetic and electronic properties at the gamma-Al2O3/SrTiO3 interface