Topological insulators (TIs) are of particular interest in the recent solid‐state research because of their exceptional features stemming from the conducting, topologically protected surface states. The exotic properties include the occurrence of novel quantum phenomena and make them promising materials for spintronics and quantum computing applications. Theoretical studies have provided a vast amount of valuable predictions and proposals, whose experimental observation and implementation, to date, are often hindered by an insufficient sample quality. The effect of even a relatively low concentration of defects can make the access to purely topological surface states impossible. This points out the need of high‐quality bulk‐insulating materials with ultra‐clean surfaces/interfaces, which requires sophisticated sample/device preparations as well as special precautions during the measurements. Herein, the challenging work on 3D TI thin films with a focus on is reported. It covers the optimization of the molecular beam epitaxy growth process, the in situ characterization of surface states and transport properties, the influence of exposure to ambient gases and of capping layers, as well as the effect of interfacing TI thin film with magnetic materials.

This paper describes a conservation of momentum experiment using just smartphones and two beach balls, thus making the experimental study of this movement available to any classroom. For a more thorough analysis of the data, a computer can also be used. Experiments making use of smartphone sensors have been described before, contributing to an improved teaching of classical mechanics. In this experiment, we have made use of two smartphone cameras together with the VidAnalysis free app to track the position of two balls colliding in air during a projectile motion (Fig. 1).

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Relying on the magnetism induced by the proximity effect in heterostructures of topological insulators and magnetic insulators is one of the promising routes to achieve the quantum anomalous Hall effect. Here, we investigate heterostructures of Bi2Te3 and Fe3O4. By growing two different types of heterostructures by molecular beam epitaxy, Fe3O4 on Bi2Te3 and Bi2Te3 on Fe3O4, we explore differences in chemical stability, crystalline quality, electronic structure, and transport properties. We find the heterostructure Bi2Te3 on Fe3O4 to be a more viable approach, with transport signatures in agreement with a gap opening in the topological surface states.