Topologically protected states in 2D and 3D: spin-momentum and valley-momentum locking mechanisms
Семинары
Семинар «Теория адронного вещества при экстремальных условиях»
Дата и время: среда, 25 октября 2017 г., в 14:30
Место: Конференц-зал им. Блохинцева (4-й этаж), Лаборатория теоретической физики им. Н.Н. Боголюбова
Тема семинара: «Topologically protected states in 2D and 3D: spin-momentum and valley-momentum locking mechanisms»
Докладчик: Maksim Ulybyshev (Regensburg U.)
Аннотация:
Topological insulator is a special state of matter which has a gap in the bulk, but hosts gapless surface modes protected by non-tirivial topological invariant. Spin-momentum and valley-momentum locking mechanisms (the former one caused by strong spin-orbital coupling) are the underlying physical reasons for the appearance of the non-trivial topology of the surface modes. Topological protection suppresses the backscattering for electronic states on the surface thus leading to promising potential applications in «dissipationless» electronic and spintronic devices. We will review the basic concepts in the field and the most prominent lattice models hosting the topologically protected modes. Namely, we will describe the Kane-Mele model on hexagonal lattice in two dimensions and some lattice models on square and diamond lattices in three dimensions. We will also describe the possibilities for artificial engineering of topological insulators with both spin- and valley-momentum locking mechanisms using the deposition of adatoms in top of graphene sheet.
The stability of topological insulator against the effects of disorder and electron-electron interaction will be discussed. Some connections to Lattice QCD will be also reviewed. For instance, the prominent Wilson fermions in some region of parameters mimic the presence of spin-orbital coupling and can be used as a model for 3D topological insulator.