quantum phase transitions; metal-insulator transitions and other electronic transitions; galvanomagnetic and other magnetotransport effects

摘要

We investigate the crossover regime from three-dimensional topological insulators Bi_2Te_3 and Bi_2Se_3 to two-dimensional topological insulators with quantum spin Hall effect when the layer thickness is reduced. Using both analytical models and first-principles calculations, we find that the crossover occurs in an oscillatory fashion as a function of the layer thickness, alternating between topologically trivial and nontrivial two-dimensional behavior.