Selected publications:

M. Niwata, R. Masutomi, T. Okamoto
Magnetic-field-induced superconductivity in ultrathin Pb films with magnetic impurities
Phys. Rev. Lett. 119, 257001 (2017); arXiv: 1710.08210.

R.Masutomi, T. Okamoto
Adsorbate-induced quantum Hall system probed by scanning tunneling spectroscopy combined with transport measurements
Appl. Phys. Lett. 106, 251602 (2015).

T. Sekihara, T. Miyake, R. Masutomi, T. Okamoto
Effect of Parallel Magnetic Field on Superconductivity of Ultrathin Metal Films Grown on a Cleaved GaAs Surface
J. Phys. Soc. Jpn. 84, 064710 (2015); arXiv: 1710.08212.

T. Sekihara, R. Masutomi, T. Okamoto
Two-dimensional superconducting state of monolayer Pb films grown on GaAs(110) in a strong parallel magnetic field
Phys. Rev. Lett. 111, 057005 (2013); arXiv:1307.2951.

T. Chiba, R. Masutomi, K. Sawano, Y. Shiraki, T. Okamoto
In-plane magnetic field dependence of cyclotron relaxation time in a Si two-dimensional electron system
Phys. Rev. B 86, 045310 (2012); arXiv:1307.2955.

R. Masutomi, K. Sasaki, I. Yasuda, A. Sekine, K. Sawano, Y. Shiraki, T. Okamoto
Metallic Behavior of Cyclotron Relaxation Time in Two-Dimensional Systems
Phys. Rev. Lett. 106, 196404 (2011); arXiv:1105.4778.

K. Sasaki, R. Masutomi, K. Toyama, K. Sawano, Y. Shiraki, T. Okamoto
Well-width dependence of valley splitting in Si/SiGe quantum wells
Appl. Phys. Lett. 95, 222109 (2009); arXiv:0911.1847.

T. Okamoto, K. Sasaki, K. Toyama, R. Masutomi, K. Sawano, Y. Shiraki
Insulating Phases Induced by Crossing of Partially Filled Landau Levels in a Si Quantum Well
Phys. Rev. B 79, 241302(R) (2009); arXiv:0903.0486.

T. Mochizuki, R. Masutomi, T. Okamoto
Evidence for Two-Dimensional Spin-Glass Ordering in Submonolayer Fe Films on cleaved InAs surfaces
Phys. Rev. Lett. 101, 267204 (2008); arXiv:0810.4425.

K. Toyama, T. Nishioka, K. Sawano, Y. Shiraki, T. Okamoto
Electronic Transport Properties of the Ising Quantum Hall Ferromagnet in a Si Quantum Well
Phys. Rev. Lett. 101, 016805 (2008); arXiv:0802.3756.

M. Minowa, R. Masutomi, T. Mochizuki, T. Okamoto
Alkali-metal-induced Fermi-level and two-dimensional electrons at cleaved InAs(110) surfaces
Phys. Rev. B 77, 233301 (2008); arXiv:0803.4448.

Y. Komori, S. Sakuma*, T. Okamoto
Ettingshausen effect around Landau level filling factor \nu=3 studied by dynamic nuclear polarization
Phys. Rev. Lett. 99, 146807 (2007) ; cond-mat/0703325 .
(*His family name has changed. Present: S. Yamamoto)

R. Masutomi, M. Hio, T. Mochizuki, T. Okamoto
Quantum Hall effect at cleaved InSb surfaces and low-temperature annealing effect
Appl. Phys. Lett. 90, 202104 (2007); cond-mat/0703670.

Y. Komori, T. Okamoto
Dynamic nuclear polarization induced by hot electrons
Appl. Phys. Lett. 90, 032102 (2007); cond-mat/0610102.

J. Matsunami, M. Ooya, T. Okamoto
Electrically detected electron spin resonance in a high mobility silicon quantum well
Phys. Rev. Lett. 97, 066602 (2006) ; cond-mat/0512041.

Y. Kawano, T. Okamoto
Noise-voltage mapping by a quantum-Hall electrometer
Appl. Phys. Lett. 87, 252108 (2005).

Y. Kawano, T. Okamoto
Macroscopic Channel-Size Effect of Nonequilibrium Electron Distributions in Quantum Hall Conductors
Phys. Rev. Lett. 95, 166801 (2005).

M. Ooya, K. Toyama, T. Okamoto
Magnetoresistance and spin polarization in the insulating regime of a Si two-dimensional electron system
Phys. Rev. B 72, 075344 (2005); cond-mat/0507136.

Y. Tsuji, T. Mochizuki, T. Okamoto
Two-dimensional electrons at a cleaved semiconductor surface: Observation of the quantum Hall effect
Appl. Phys. Lett. 87, 062103 (2005); cond-mat/0507135.

Y. Komori, T. Okamoto
Observation of the Ettingshausen effect in quantum Hall systems
Phys. Rev. B 71, 113306 (2005); cond-mat/0407551.

Y. Tsuji, T. Okamoto
Magnetotransport measurements on a damaged surface of p-type InAs and the annealing effect
Phys. Rev. B 70, 245316 (2004).

Y. Kawano, T. Okamoto
Imaging of intra- and inter-Landau-level scattering in quantum Hall systems
Phys. Rev. B 70, 081308R (2004).

T. Okamoto, M. Ooya, K. Hosoya, S. Kawaji
Spin polarization and metallic behavior in a silicon two-dimensional electron system
Phys. Rev. B 69, 041202R (2004); cond-mat/0307521.

Y. Kawano, T. Okamoto
Scanning electrometer using the capacitive coupling in quantum Hall effect devices
Appl. Phys. Lett. 84, 1111 (2004).