|
|
Topological insulators and magnetic order
Šebesta, Jakub ; Carva, Karel (advisor) ; Hamrle, Jaroslav (referee) ; Železný, Jakub (referee)
The occurrence of various defects can strongly influence the physical properties of real materials. Depending on their type, new outstanding features can arise, but also charac- teristic behavior might be lost. This thesis is dedicated to the impact of diverse disorder's presence on the physical behavior of three-dimensional topological insulators, namely, the well-known Bi2Se3 compound. Despite possessing a band gap in the bulk, these materials host unique metallic surface states protected by the time-reversal symmetry. Thus, the surface states are robust against perturbation, which respects the protecting symmetry. Breaking the symmetry, e.g. by the magnetic field, can open the surface gaps. In this work, the influence of the magnetic as well as native chemical defects, occurring in the real samples, on the electronic structure is described. Notably, the dispersion of the sur- face metallic states is followed up. Since the surface gap can be opened by the magnetic field, magnetic exchange interactions and related Curie temperatures of magnetic defects are thoroughly studied. Particularly, the influence of disorder on the character of the exchange interactions and related Curie temperatures is described. Dealing with layered systems, the behavior of planar defects might be inspected. Therefore, the...
|
guest ::
