Department of Electrical Engineering and Information Systems, The University of Tokyo
TOPOLOGICAL QUANTUM ELECTRONICS LABORATORY
At Anh Lab, we aim to integrate dissimilar material systems utilizing our unique capability of
epitaxial growth of thin film heterostructures using molecular beam epitaxy (MBE) and device nano-fabrication.
Some recent research topics are:
Study on crystal growth of non-magnetic / ferromagnetic semiconductor heterostructures, and realization of new spin-dependent physics and devices, such as tunnel magnetoresistance effect (TMR) and giant magnetoresistance effect (GMR).
New proximity magnetoresistance (PMR) and related physics at high-mobility InAs/ ferromagnetic semiconductor (Ga,Fe)Sb bilayer structures.
First realization of high mobility 2D hole channels on SrTiO3 by transition-metal deposition.
Realization of elemental topological Dirac semimetal α-Sn with highest mobility thus far, and research on its topological transport phenomena.
Study on Andreev reflection at superconductor/ferromagnetic semiconductor interfaces.
Epitaxial growth of superconducting metal / ferromagnetic semiconductor heterostructures for creation of topological superconductivity and Majorana bound states.
Illustration of MBE growth process
(Courtesy of prof. Shinobu Ohya)
Ongoing Research Projects
- To make semiconductor ferromagnetic -
We aim to utilize the spin degrees of freedom in artificially synthesized materials, with the main spotlight shed on ferromagnetic semiconductors (FMSs). FMSs are semiconductors doped with a large amount of magnetic elements, which inherit special features of both semiconductors and ferromagnets.
We are studying epitaxial growth, structural characterizations, electronic/optical/magnetic/spin-related properties of these structures and their applications in power-saving electronic devices.
Superconductor/Ferromagnetic Semiconductor Hybrid Structures
- Searching for Majorana on magnetic semiconductors -
We aim to integrate "Superconductivity" and "Ferromagnetism" onto a single semiconductor platform, by developing heterostructures of s-wave superconductors (SC) and Fe-doped ferromagnetic semiconductors (FMS). It has been predicted that there exist Majorana bound states, novel topological states that are the anti-particle of themself, which are the holygrails of topological quantum computing. By omitting the necessity of applying external magnetic field, our system is unique in the field and promising for scalable quantum computation.
We are conducting epitaxial growth and structural characterizations of the SC/FMS systems, fabrication of nanosize junction structures, and measurements at ultralow (mK) temperature.
Exploring new topological materials
- Expanding the horizon of Dirac materials and physics-
We exploring the growth and novel physics of new topological materials, including topological Dirac and Weyl semimetals, topological insulators, and their heterostructures.
Our works extend beyond crystal growth and fundamental physics, with a keen eye on possible applications of these fascinated topological phenomena to sensing devices, information processing and storage techniques in the future.
- Interfaces where oxygen is vital -
We develop oxide-based devices utilizing functional oxide materials and high-mobility transport channels at their interfaces, in which the control of oxygen atoms plays a vital role. These interfacial channels are promising for high efficient spin-to-charge conversion, high-speed transistors, and flexible electronic devices.