Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 17: Poster Session: Correlated Electrons 1

TT 17.28: Poster

Montag, 1. April 2019, 15:00–18:30, Poster D

Two-dimensional electron gas at the KTaO₃ surface and KTaO₃/EuO interface — •Xue-Jing Zhang¹ and Bang-Gui Liu² — ¹Institute for Advanced Simulation, Forschungszentrum Jülich, D-52425 Jülich, Germany — ²Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

Since the discovery of a two-dimensional (2D) electron gas at the LaAlO₃/SrTiO₃ interface, 2D carrier gases at such oxide interfaces and surfaces have attracted great attention because they can host many important phenomena and may produce novel functional devices. Here, we show through first-principles investigations that the surface 2D electron and hole gases in a KTaO₃ (KTO) thin film can be tuned by applying biaxial stress. When increasing compressive in-plane strain, the 2D carrier concentrations decrease down to zero and then a new pair of surface 2D electron and hole gases appears in which the carrier types are switched to the opposite ones. Our analysis indicates that this carrier-type switching occurs because the increasing compressive strain reverses the slope of monolayer-resolved electrostatic potential along the [001] direction. In addition, through first-principles investigations, we also study the KTO/EuO interfaces with oxygen vacancies in the KTO unit cell adjacent to EuO. We find that through interlayer exchange of the Eu-5d and Ta-5d, EuO drives the neighboring TaO₂ layer into a ferromagnetic state. These phenomena should be useful to design novel functional devices.