Manganese Doped Topological Insulators

Abstract

When a topological insulator is incorporated with magnetism, the time-reversal symmetry (TRS) breaks. This chapter sums up the current research in Mn-doped topological insulators, mostly focusing on antiferromagnetic MnBi2Te4 and its family. Specific critical behavior of Mn-doped Bi2Te3 topological insulator reveals ferromagnetic ordering (to increase conductivity) of Mn spin at normal substitution. Moreover, due to intrinsic anti-state substitutional defect if a comparable amount of local moment is produced then calculated data is in favor of a spin glass state with polarization. Exotic phenomena like the magnetoelectric effect and dissipation less edge state occur in this material and to study MnBi2Se4 epitaxial thin films a scanning tunneling microscope (STM) is utilized. Steps between a screw dislocation and the van der Waals layer are manifested in the large-scale topographic image. In a small area at the edge Bi termination is occurred and Se termination is dominant at the surface, this termination is compared by examining step height, tunneling spectroscopy, and resolution image. Similarly, for analyzing Mn impurity in Bi2Se3 electron paramagnetic resonance is used and by implementing the vertical Bridgman method topological insulator is grown. Mn2+ configuration was found in conducting state of a host metal and Mn in high spin =5/2Mn^(2+). This assumption shows that energy level Mn^(2+) (d^5) is present the valence bad (VB) and energy level, Mn^(1+) (d^6) is located far way form energy gap.