| PI Name | Minoru Kawamura | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Title | Team Leader | ||||||||||||||
| Brief Resume |
|||||||||||||||
|
|||||||||||||||
We study various quantum transport phenomena in electronic systems in solids. In particular, we focus on thin film crystals and heterostructures of materials with non-trivial band structure topology and strong spin-orbit interactions, and study phenomena in which electronic correlation and/or geometrical phase play an important role. Through these studies, we aim to discover new quantum phenomena that will advance our understanding of condensed matter physics, and to explore electronic and spintronic functions using these phenomena, opening the door to new technologies.
Physics, Engineering, Materials Sciences
Topological insulators
Topological superconductors
Thin films and interfaces
Quantum transport phenomena
Anomalous Hall effect
Topological insulators are a group of materials that have a metallic surface state, although the interior of the material is an insulator. In magnetic topological insulators doped with magnetic elements, the resistance perpendicular to the current (Hall resistance) becomes the quantum unit of electrical resistance, the von Klitzing constant (h/e2, where h is Planck’s constant and e is the elementary charge). This phenomenon known as the quantum anomalous Hall effect occurs even in the absence of an external magnetic field, it is expected to be applied to a new type of quantum resistive standard element that does not require a strong magnetic field.
In this study, we synthesized thin films of magnetic topological insulator heterostructures using molecular beam epitaxy. In collaboration with a research team from the National Institute of Advanced Industrial Science and Technology, we measured the accuracy of the quantum anomalous Hall effect by using a commercially available small permanent magnet to align the magnetic domains of the sample. We found that the accuracy of the quantum anomalous Hall resistance is 8 digits, which is very high and equivalent to the level of the national measurement standard. By eliminating the need for a strong magnetic field, it is possible to miniaturize the most accurate resistance standard, and it is expected to be used in a variety of fields, including private companies.
(Left) Schematic illustration of the quantum anomalous Hall effect device with a small permanent magnet was used to align the magnetic domains. (Right) Temperature dependence of the longitudinal (Rxx) and Hall (Ryx) resistance. The quantum anomalous Hall effect with Ryx is seen below 1 Kelvin.
Minoru Kawamura |
Team Leader |
|---|
Laughlin charge pumping in a quantum anomalous Hall insulator
Experimental signature of the parity anomaly in a semi-magnetic topological insulator
Quantum anomalous Hall effect with a permanent magnet defines a quantum resistance standard
Topological quantum phase transition in magnetic topological insulator upon magnetization rotation
A magnetic heterostructure of topological insulators as a candidate for an axion insulator
Electron-bending effect could boost computer memory
2-1 Hirosawa, Wako, Saitama 351-0198 Japan
E-mail：
minoru[at]riken.jp
2-1 Hirosawa, Wako, Saitama 351-0198 Japan
TEL：+81-(0)48-462-1111
(Switchboard Number)
FAX：+81-(0)48-462-1554
Copyright © RIKEN Center for Emergent Matter Science. All Rights Reserved.