Topological insulators (TIs) are materials that conduct only via its topologically protected states on the boundary. Precise theoretical predictions, along with well-controlled material growths and characterizations, have led to the discovery of a series of topological insulators, such as the HgTe quantum well and Bi2Se3 family. In this talk, I will introduce the growth, characterization, and fabrication techniques of both 3D and 2D TIs, and discuss the exotic phenomena in transport studies. By constructing a magnetically doped 3D TI sandwich heterostructure, such that the top and bottom magnetic layers have distinct coercive fields, both the quantum anomalous Hall effect and the axion insulator state can be observed, when the magnetization alignment of the top and bottom layers is parallel and antiparallel, respectively. Another interesting result comes from a 2D TI system made of more conventional III-V semiconductor material, type-II InAs/GaSb quantum wells. By tuning relevant parameters, such as front/back gate voltages and thicknesses of the channel layers, one is able to enter a new insulating regime, with seemingly controversial high-density states, which can be explained by the effect of the attractive Coulomb interaction.
Brief CV of Dr. Di Xiao:
Dr. Di Xiao is a postdoc associate in Prof. Michael Manfra’s group at Station Q Purdue and Department of Physics and Astronomy, Purdue University. He received his doctoral degree from Pennsylvania State University in 2019 under the supervision of Prof. Nitin Samarth. His current research interest is focused on the growth and fabrication of planar III-V semiconductor and superconductor materials, searching for the elusive Majorana fermions.
Contact: Shujuan Cui (崔书娟）
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