RESEARCH

I have investigated the response of topologically protected Andreev bound states appearing at a surface of superfluid ³He to transverse acoustic wave. In p-wave superfluids, surfaces and impurities act as strong pair brakers. As a result, unusual quasiparticle states are expected around such surfaces and impurities. In particular at a surface of superfluid ³He, it is turned out that the bound state is described by unusual excitation so called Majorana fermion excitation as well as it is in the noncentrosymmetric superconductors (studied in Group C01) and in the chiral superconductor (studied in Group A01). To study features of the Majorana fermion modes in ³He, we have measured the acoustic impedance. The transverse acoustic impedance is a unique surface probe which tells us spectroscopic details of the surface density of states.

In this project, I will investigate effects of external magnetic field on the Majorana surface bound states in superfluid ³He-B phase. In addition, I try to find new phases which are stabilized in the presence of magnetic field.

EDUCATION

1991

Bachelor of Science, Kyoto University

2000

Ph.D. (Physics), Kyoto University

PROFESSIONAL EXPERIENCE

1998-2000

Research fellow, Northwestern University

2000-2007

Research associate, Graduate School of Science, Tokyo Institute of Technology

2007-Present

Assistant Professor, Department of Physics, Tokyo Institute of Technology

HONORS AND AWARDS

2007

Young Scientist Award of Physical Society of Japan

SELECTION OF PUBLICATIONS

"Ripening of Splashed ⁴He Crystals by Acoustic Waves with and without Gravity",
T. Takahashi, H. Ohuchi, R. Nomura, and Y. Okuda
New J. Phys. 14, 123023-1-11 (2012).

"Surface Andreev bound states of superfluid ³He and Majorana Fermions",
Y. Okuda and R. Nomura
J. Phys.: Cond. Matt. 24, 343201-1-19 (2012). Topical Review

"Strong suppression of the Kosterlitz-Thouless transition in a ⁴He film under high pressure",
S. Murakawa, M. Wasai, K. Akiyama, Y. Wada, Y. Tamura, R. Nomura and Y. Okuda
Phys. Rev. Lett. 108, 025302 (2012).

"Surface Majorana Cone of the Superfluid ³He B Phase",
S. Murakawa, Y. Wada, Y. Tamura, M. Wasai, M. Saitoh, Y. Aoki, R. Nomura, Y. Okuda, Y. Nagato, M. Yamamoto, S. Higashitani, and K. Nagai
J. Phys. Soc. Jpn. 80, 013602-1-4 (2011).

"New anomaly in the transverse acoustic impedance of superfluid ³He-B with a wall coated by several layers of ⁴He",
S. Murakawa, Y. Tamura, Y. Wada, M. Wasai, M. Saitoh, Y. Aoki, R. Nomura, Y. Okuda, Y. Nagato,M. Yamamoto, S. Higashitani, and K. Nagai,
Phys. Rev. Lett. 103, 155301(1)-(4) (2009).

"Broadening of the surface Andreev bound states band of superfluid ³He-B on a partially specular wall",
Y. Wada, S. Murakawa, Y. Tamura, M. Saitoh, Y. Aoki, R. Nomura, and Y. Okuda,
Phys. Rev. B 78, 214516(1)-(5) (2008).

"Competition between thermal fluctuations and disorder in the crystallization of ⁴He in aerogel",
R. Nomura, A. Osawa, T. Mimori, K. Ueno, H. Kato, and Y. Okuda,
Phys. Rev. Lett. 101, 175703(1)-(4) (2008).

"Observation of Surface Andreev Bound States of Superfluid ³He by Transverse Acoustic Impedance Measurements",
Y. Aoki, Y. Wada, M. Saitoh, R. Nomura, Y. Okuda, Y. Nagato, M. Yamamoto, S. Higashitani, and K. Nagai,
Phys. Rev. Lett. 95, 075301(1)-(4) (2005).

"Interface Motion and Nucleation of Solid Helium-4 Induced by Acoustic Waves",
R. Nomura, Y. Suzuki, S. Kimura, and Y. Okuda,
Phys. Rev. Lett. 90, 075301(1)-(4) (2003).