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Zusammenfassung:
Two-dimensional electron gases (2DEGs) formed at the interface of
insulating complex oxides promise the development of all-oxide
electronic devices. These 2DEGs involve many-body interactions that give
rise to a variety of physical phenomena such as superconductivity,
magnetism, tunable metal-insulator transitions and phase separation.
Increasing the mobility of the 2DEG, however, remains a major challenge.
Here, we show that the electron mobility is enhanced by more than two
orders of magnitude by inserting a single-unit-cell insulating layer of
polar La1-xSrxMnO3 (x = 0, 1/8, and 1/3) at the interface between
disordered LaAlO3 and crystalline SrTiO3 produced at room temperature.
Resonant X-ray spectroscopy and transmission electron microscopy show
that the manganite layer undergoes unambiguous electronic
reconstruction, leading to modulation doping of such atomically
engineered complex oxide heterointerfaces. At low temperatures, the
modulation-doped 2DEG exhibits Shubnikov-de Haas oscillations and
fingerprints of the quantum Hall effect, demonstrating unprecedented
high mobility and low electron density.
