Electronic states at surfaces, interfaces, and edges of materials emerge due to different reasons and have their own characters, which are expected to be useful for intriguing physics and possible applications to electronic/spintronics devices. Especially emerging quantum materials, such as graphene and similar monatomic-layer materials, van der Waals two-dimensional crystals, and topological insulators, show prominent features in the surface/edge states. Such states at the boundaries are different from those inside the three- or two-dimensional crystals, because of the truncation of crystal lattice periodicity, space-inversion-symmetry breaking, and difference in topology in band structures across the boundaries. Such quantum materials are expected to be key ingredients for energy-saving/-harvesting technology as well as quantum computation/information technology. This is based on exotic phenomena at the states, such as spin–momentum locking of electrons, dissipation-less charge/spin currents, nonreciprocal current, and possible Majorana fermions. In this presentation, the fundamental concepts of such surface/edge states are introduced from the viewpoint of surface physics. Especially charge and spin-related transport properties are discussed based on controls of the atomic and electronic structures of materials by using state-of-the-art techniques.
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The author is preparing a supplementary material as a response to the reviewers, which will be published shortly after the publication of the video article.
