Members Profile

Ryota Akiyama

Ryota Akiyama

Assistant Professor, Graduate School of Science, the University of Tokyo

Development of monolayer topological insulators and exploring concert effects in superconductive interfaces

E-mail : akiyama[at]


I have researched magnetic semiconductors, magnetic materials such as chalcogenides for spintronics from the aspects of structures, magnetism and electrical transports before I began the theme of topological insulator. In topological insulator field, I have investigated SnTe group known as a topological crystalline insulator. I measured the surface band with APRES and electrical transports by the 2-dimensional weak antilocalization. I use actively the high magnetic fields, and have investigated Shubnikov de-Haas oscillation in(BixSb1-x)2Te3, topological insulator.

The topological states induced at the interface or the surface has attracted attention much these days. Because the surface state is easy to be broken due to the oxidation or molecular-adsorption the in situ electrical transport measurements in ultrahigh vacuum environment enable us to investigate the more intrinsic properties about topological insulators. I aim to reveal the relation between the topological surface state and the surface structure with using STM as well. In addition, I explore the 2D topological insulator which appears if the thickness becomes monolayer in topological crystalline insulators. The heterostructure of the topological insulator and the superconductor is also interesting because the topological superconductivity or the Majorana state is predicted at the interface, and I am trying to investigate such novel phenomena.


B.Sc. in Physics, Waseda University
M.S. in Physics, the University of Tokyo
Ph.D. in Physics, the University of Tokyo


Assistant Professor, Graduate School of Science, University of Tsukuba
Assistant Professor, Graduate School of Science, the University of Tokyo


Best presentation award in 1st annual meeting of cryogenic research center, the Univ. of Tokyo


"Thin film growth of a topological crystal insulator SnTe on the CdTe (111) surface by molecular beam epitaxy"
Ryo Ishikawa, Tomonari Yamaguchi, Yusuke Ohtaki, Ryota Akiyama, Shinji Kuroda
Journal of Crystal Growth 453(1) 124-129 (Nov. 2016).
DOI: 10.1016/j.jcrysgro.2016.08.027

"Two-dimensional quantum transport of multivalley (111) surface state in topological crystalline insulator SnTe thin films"
Ryota Akiyama, Kazuki Fujisawa, Tomonari Yamaguchi, Shinji Kuroda
Nano Research 9(2) 490-498 (Feb. 2016).
DOI: 10.1007/s12274-015-0930-8

"Deposition and characterization of aluminum nitride thin films for a gate insulator"
H. Oikawa, R. Akiyama, K. Kanazawa, S. Kuroda, I. Harayama, K. agashima, D. Sekiba, Y. Ashizawa, A. Tsukamoto, K. Nakagawa, N. Ota
Thin Solid Films 574 110-1-5 (Dec. 2014).
DOI: 10.1016/j.tsf.2014.11.081

"Weak antilocalization in (111) thin lms of a topological crystalline insulator SnTe"
R. Akiyama, K. Fujisawa, R. Sakurai, S. Kuroda
Journal of Physics: Conference Series 568 052001-1-6 (Aug. 2014).
DOI: 10.1088/1742-6596/568/5/052001

"Carrier transport properties of the Group-IV ferromagnetic semiconductor Ge1-xFex with and without boron doping"
Yoshisuke Ban , Yuki Wakabayashi , Ryota Akiyama , Ryosho Nakane, Masaaki Tanaka
AIP advances 4 097108-1-9 (Sep. 2014).
DOI: 10.1063/1.4895109

"Structural and magnetic characterization of (Zn,Fe)Te thin films grown by MBE"
Satoshi Ishitsuka, Takeru Domon, Ryota Akiyama, Ken Kanazawa, Shinji Kuroda, Hironori Ofuchi
physica status solidi (c) 11(7-8) 1312-1315 (Apr. 2014).
DOI: 10.1002/pssc.201300649

"Electric-field modulation of ferromagnetism in hexagonal chromium telluride thin film"
Ryota Akiyama, Haruyoshi Oikawa, Kazuma Yamawaki, Shinji Kuroda
physica status solidi (c) 11(7-8) 1320-1323 (Apr. 2014).
DOI: 10.1002/pssc.201300751

"Effect of acceptor co-doping on magnetism and electronic states in ferromagnetic semiconductor (Zn,Cr)Te"
Ke Zhang, Ryota Akiyama, Ken Kanazawa, Shinji Kuroda, Hironori Ofuchi
physica status solidi (c) 11(7-8) 1324-1327 (Apr. 2014).
DOI: 10.1002/pssc.201300755

"Magnetoresistance enhanced by inelastic cotunneling in a ferromagnetic MnAs nanoparticle sandwiched by nonmagnetic electrodes"
Ryota Akiyama, Shinobu Ohya, Pham Nam Hai, Masaaki Tanaka
Journal of Applied Physics 111 063716 1-5 (Mar. 2012).
DOI: 10.1063/1.3695990

"Short-range spin correlations in β″-LiFeO2 from bulk magnetization, neutron diffraction, and μSR experiments"
Ryota Akiyama, Yutaka Ikedo, Martin Månsson, Tatsuo Goko, Jun Sugiyama, Daniel Andreica, Alex Amato, Kittiwit Matan, and Taku J. Sato
Physical Review B 81 024404 1-9 (Jan. 2010).
DOI: 10.1103/PhysRevB.81.024404