COherent Bragg Rod Analysis of KTaO₃ surface/interface

Perovskite potassium tantalate (KTaO₃) shares many similar advantages (high dielectric constant, simple cubic structure, high mobility, etc.) with SrTiO₃ (STO). Yet it has a stronger (at least an order of magnitude higher) spin-orbit coupling (SOC) than STO, which will lead to exciting electronic and magnetic properties at the interface of KTO-based heterostructures [1]. Unlike the well-defined STO surface with TiO₂ termination, KTaO₃ (KTO) possess charged layers of KO and TaO₂ along 001 direction. By annealing in vacuum, it allows the formation of isolated oxygen vacancies, followed by a complete rearrangement of the top layers into an ordered pattern of KO and TaO₂ stripes [2]. Here we used COherent Bragg Rod Analysis (COBRA) method to reconstruct the electron densities at the KTO surfaces/interfaces. The results with different orientations ((001) and (111)) were compared. And we also measured and analyzed its interfaces with LaAlO₃ and EuO films. These important interpretations on the KTO surfaces/interfaces could further serve as a working model for revealing its fascinating properties.



[1] C. J. Liu, et al., Science 371, 716-721 (2021).

[2] Setvin et al., Science 359, 572–575 (2018).