Topological quantum weak antilocalization limit and anomalous Hall effect in semimagnetic Bi2−xCrxSe3/Bi2Se3−yTey heterostructure

Abstract

Magnetic topological insulator hosts both a non-trivial surface band and quantum anomalous Hall effect when tuning the time reversal symmetry by various chemical doping into the system. Using molecular beam epitaxy, we have synthesized Bi _2−x Cr _x Se _3 /Bi _2 Se _3−y Te _y heterostructure, which was scrutinized via in situ angle resolved photoemission spectroscopy, ex situ x-ray diffraction, Raman, and x-ray photoemission characteristics analyzing techniques. We used the Hikami-Larkin-Nagaoka formula for quantifying the weak antilocalization limit in Bi _2−x Cr _x Se _3 and Bi _2 Se _3−y Te _y non-magnetic layer coupling near the ferromagnetic transition temperature (∼7 K). A higher concentration of Cr (1.5%) in Bi site leads to bulk carrier density for entire cooling temperature with a bandgap of 85 meV. The proximity effect of Te doped Bi _2 Se _3 with magnetic topological insulator degrades the ferromagnetic response for this heterostructure. Our study suggests that the manipulation of disorder free magnetic top layer and fine tuning of spin–orbit coupling strength in the bottom topological insulator can be helpful to understand the high temperature quantum anomalous Hall effect towards relativistic quantum electronics applications.

Keywords

• magnetic topological insulator
• epitaxial growth
• proximity effect
• quantum anomalous Hall effect
• weak antilocalization