RESEARCH

My research field is the spin/orbital degrees of freedom in correlated electron system. Specifically, I have been searching novel spin/orbital ordering phenomena and Dirac/Weyl semimetal in Mott transition materials. By combining the material synthesis and spectroscopic technique including terahertz/infrared optics or X-ray scattering, I am aiming at searching novel quantum phenomena from micro/macroscopic view points.

I am experimentally searching novel topological quantum phenomena by developing new materials including 5d-electron systems.

EDUCATION

2004

B.Sc. in Physics, the University of Tokyo

2008

M.S. in Physics, the University of Tokyo

PROFESSIONAL EXPERIENCE

2008-2009

JSPS Fellow (PD)

2009-2011

Japan Science and Technology Agency Fellow

2011-2013

Present Lector, Dept. of Applied Phys., the University of Tokyo

2013

Research Associate, Dept. of Applied Phys., the University of Tokyo

2015-2019

Researcher, PRESTO Japan Science and Technology Agency

2018-present

Associate Professor, Faculty of Pure and Applied Sciences, University of Tsukuba

HONORS AND AWARDS

2019

Young Scientist Award of the Physical Society of Japan

2019

Young Teacher Award, University of Tsukuba

SELECTION OF PUBLICATIONS

"Enhanced thermopower in the correlated semimetallic phase of hole-doped pyrochlore iridates"
R. Kaneko, M.-T. Huebsch, S. Sakai, R. Arita, H. Shinaoka, K. Ueda, Y. Tokura, and J. Fujioka,
Physical Review B 99, 161104(R)-1-5 (Apr. 2019).
DOI:10.1103/PhysRevB.99.161104

"Strong-correlation induced high-mobility electrons in Dirac semimetal of perovskite oxide"
J. Fujioka, R. Yamada, M. Kawamura, S. Sakai, M. Hirayama, R. Arita, T. Okawa, D. Hashizume ,M. Hoshino and Y. Tokura,
Nature Communications 10, 362-1-6 (Jan. 2019).
https://doi.org/10.1038/s41467-018-08149-y

"Spontaneous Hall effect in the Weyl semimetal candidate of all-in all-out pyrochlore iridate"
K. Ueda, R. Kaneko, H. Ishizuka, J. Fujioka, N. Nagaosa and Y. Tokura
Nature Communications 9, 3032 (Aug. 2018).
DOI: 10.1038/s41467-018-05530-9

"Magnetic-field induced multiple topological phases in pyrochlore iridates with Mott criticality"
K. Ueda, T. Oh, B. Yang, R. Kaneko, J. Fujioka, N. Nagaosa, and Y. Tokura,
Nature Communications 8, 15515-1-7 (Mar. 2017).
DOI: 10.1038/ncomms15515

"Correlated Dirac semimetallic state with unusual positive magnetoresistance in strain-free perovskite SrIrO₃"
J. Fujioka, T. Okawa, A. Yamamoto, and Y. Tokura,
Physical Review B 95, 121102(R)-1-5 (Mar. 2017).
DOI:10.1103/PhysRevB.95.121102

"Variation of optical conductivity spectra in the course of bandwidth-controlled metal-insulator transitions in pyrochlore iridates"
K. Ueda, J. Fujioka, Y. Tokura,
Physical Review B, 93, 245120-1-10 (Jun. 2016).
DOI: 10.1103/PhysRevB.93.245120

"Strain-sensitive spin-state ordering in thin films of perovskite LaCoO₃"
J. Fujioka, Y. Yamasaki, A. Doi, H. Nakao, R. Kumai, Y. Murakami, M. Nakamura, M. Kawasaki, T. Arima, and Y. Tokura,
Physical Review B 92, 195115-1-6 (Nov. 2015).
DOI: 10.1103/PhysRevB.92.195115

"Mobile metallic domain walls in an all-in-all-out magnetic insulator"
E. Y. Ma, Y-T Cui, K. Ueda, S. Tang, K. Chen, N. Tamura, P. M. Wu, J. Fujioka, Y. Tokura, Z-X. Shen,
Science 350, 538-1-5 (Oct. 2015).
DOI: 10.1126/science.aac8289

"Pressure and magnetic field effects on metal-insulator transitions of bulk and domain wall states in pyrochlore iridates"
K. Ueda, J. Fujioka, C. Terakura, Y. Tokura,
Physical Review B, 92, 121110-1-5 (Sep. 2015).
DOI: 10.1103/PhysRevB.92.121110

"Ferroelectric-like metallic state in electron doped BaTiO₃"
J. Fujioka, A. Doi, D. Okuyama, D. Morikawa, T. Arima, K. N. Okada, Y. Kaneko,T. Fukuda, H. Uchiyama, D. Ishikawa, A. Q. R. Baron, K. Kato, M. Takata and Y. Tokura,
Scientific Reports 5, 13207-1-9 (Aug. 2015).
DOI: 10.1038/srep13207

"Anomalous domain-wall conductance in pyrochlore-type Nd₂Ir₂O₇ on the verge of the metal-insulator transition"
K. Ueda, J. Fujioka, Y. Takahashi, T. Suzuki, S. Ishiwata, Y. Taguchi, M. Kawasaki, and Y. Tokura,
Physical Review B、89, 075127-1-5 (Feb. 2014).
DOI: 10.1103/PhysRevB.89.075127

"Spin-Orbital Superstructure in Strained Ferrimagnetic Perovskite Cobalt Oxide"
J. Fujioka, Y. Yamasaki, H. Nakao, R. Kumai, Y. Murakami, M. Nakamura, M. Kawasaki, and Y. Tokura,
Physical Review Letters 111, 027206-1-5 (Jul. 2013).
DOI: 10.1103/PhysRevLett.111.027206

"Variation of Charge Dynamics in the Course of Metal-Insulator Transition for Pyrochlore-Type Nd2Ir2O7"
K. Ueda, J. Fujioka, Y. Takahashi, T. Suzuki, S. Ishiwata, Y. Taguchi, and Y. Tokura,
Physical Review Letters 109, 136402-1-5 (Sep. 2012).
DOI: 10.1103/PhysRevLett.109.136402