||Development of fabrication technology for topological insulators for their possible use in spintronics and quantum computers
||Nanotechnologies and Nanomaterials
||Ghitu Institute of Electronic Engineering and Nanotechnologies, ASM
||Konopko Leonid, doctor, associated professor (docent)
||Laboratory of Electronics of Low Dimensional Structures
||Surface states, spin-orbit interaction, topological insulator, thermoelectricity
The objective of this project is the design of crucially new devices using a novel class of materials of solid state physics, i.e., topological insulators whose theoretical prediction in 2007 and experimental evidence in 2008 excited a great interest in these unique materials at the present day. On the surfaces of topological insulators, electrons move with little or no resistance. Thus, with less energy consumption, it is possible to obtain a higher efficiency of electron motion than in modern electronic devices.
An important requirement for the practical use of topological insulators is their preparation with a desired crystallographic orientation; for this purpose, we will develop a technology for producing nanowires using laser and zone recrystallization techniques as well as recrystallization in a magnetic field.
A significant increase in ZT in the low-dimensional structures was theoretically predicted. Recently, it was shown that Bi2Te3 and Bi2Se3 crystals are topological insulators and their surface states consist of a single Dirac cone; this offers a challenge of using Bi2Te3 and Bi2Se3 nanowires in thermoelectricity.
In a temperature range of 300 - 4 K, the thermopower of obtained nanowires of topological insulators will be measured (particularly, under the effect of magnetic and transverse electric fields as well as uniaxial tension and compression) in order to obtain a material with high thermoelectric efficiency.
From the measurement of the Aharonov-Bohm oscillations and the Berry phase for Bi nanowires, we proved the existence of surface states with only one degree of freedom for a spin, as it takes place in topological insulators. In order to study the Aharonov-Bohm oscillations and the Berry phase as a necessary condition to show the appropriateness for using in spintronics, we will study the magnetoresistance of resulting nanowires of topological insulators. To explore the possibility of using InSb and Bi nanowires in quantum computers (for the generation of topological superconducting phase), the nanowire/s-wave superconductor (e.g., Pb) interface will be studied in a weak longitudinal magnetic field.