Wide Bandgap Semiconductor Spintronics

Book excerpt: This second edition of the book presents spintronic properties of III–V nitride semiconductors. As wide bandgap III-nitride nanostructures are relatively new materials, the book pays particular attention to the difference between zinc-blende GaAs- and wurtzite GaN-based structures where the Rashba spin–orbit interaction plays a crucial role in voltage-controlled spin engineering. It also deals with topological insulators and discusses electrically driven zero-magnetic-field spin-splitting of surface electrons with respect to the specifics of electron-localized spin interaction and voltage-controlled ferromagnetism. It describes the recently identified zero-gap state—an anomalous quantum semimetal. The book comprises calculation of topological indexes in semiconductor and semimetal phases. It compares results that follow from the low-energy model and the Bernevig–Huges–Zhang model, which accounts for the full-Brillouin-zone electron spectrum. It also discusses the fractional quantization of Hall conductance and performs the direct calculation of Chern numbers for the inverted GaN/InN quantum well, determining topological properties by Chern number |C |=2. The book explores and actively discusses semiconductor spintronics and proposes various device implementations along the way. Although writings on this topic appear in the current literature, this book is focused on the materials science side of the question, providing a theoretical background for the most common concepts of spin-electron physics. It covers generic topics in spintronics without entering into device specifics since its aim is to give instructions to be used in solving problems of a general and specific nature. It is intended for graduate students and will serve as an introductory course in this specific field of solid state theory and applications.