RIKEN Center for Emergent Matter Science Dynamic Emergent Phenomena Research Unit

Unit Leader: Fumitaka Kagawa (Ph.D.)

Japanese Page

Research Summary

Our research unit explores dynamic phenomena exhibited by strongly correlated electron systems in both bulk specimen and device structures to construct a new principle in condensed matter science. In particular, we study external-field-driven dynamic phenomena exhibited by sub-micron-scale structures, such as topological spin textures and domain walls, using spectroscopy of dielectric responses and resistance fluctuations from the millihertz to gigahertz region. We also pursue real-space observations and measurements of local physical properties using scanning probe microscopy as a complementary approach. We are aiming to control novel physical properties exhibited by topological structures in condensed matter systems on the basis of knowledge obtained from these methods.

Main Research Fields

Mathematical & Physical Sciences

Related Research Fields

Interdisciplinary Science & Engineering
Engineering

Keywords

Metal-insulator transition
Phase-change memory
Scanning probe microscopy
Magnetic skyrmion

Selected Publications

1.H. Oike, M. Kamitani, Y. Tokura, and F. Kagawa.:
“Kinetic approach to superconductivity hidden behind a competing order”
Sci. Adv. 4, eaau3489 (2018)
2.H. Oike, M. Suda, M. Kamitani, A. Ueda, H. Mori, Y. Tokura, H. M. Yamamoto, and F. Kagawa.:
“Size effects on supercooling phenomena in strongly correlated electron systems: IrTe₂ and θ-(BEDT-TTF)₂RbZn(SCN)₄”
Phys. Rev. B 97, 085102 (2018)
3.F. Kagawa, H. Oike, W. Koshibae, A. Kikkawa, Y. Okamura, Y. Taguchi, N. Nagaosa, and Y. Tokura.:
“Current-induced viscoelastic topological unwinding of metastable skyrmion strings”
Nat. Commun. 8, 1332 (2017)
4.F. Kagawa and H. Oike
“Quenching of Charge and Spin Degrees of Freedom in Condensed Matter”
Adv. Mat. 29, 1601979 (2017)
5.Y. Okamura, F. Kagawa, S. Seki, and Y. Tokura.:
“Transition to and from the skyrmion lattice phase by electric fields in a magnetoelectric compound”
Nat. Commmun. 7, 12669 (2016)
6.F. Kagawa, N. Minami, S. Horiuchi, and Y. Tokura.:
“Athermal domain-wall creep near a ferroelectric quantum critical point”
Nat. Commun. 7, 10675 (2016)
7.H. Oike, A. Kikkawa, N. Kanazawa, Y. Taguchi, M. Kawasaki, Y. Tokura, and F. Kagawa.:
“Interplay between topological and thermodynamic stability in a metastable magnetic skyrmion lattice”
Nat. Phys. 12, 62 (2016)
8.Y. Okamura, F. Kagawa, S. Seki, M. Kubota, M. Kawasaki, and Y. Tokura
“Microwave Magnetochiral Dichroism in the Chiral-Lattice Magnet Cu₂OSeO_3”Phys. Rev. Lett. 114, 197202 (2015)
9.H. Oike, F. Kagawa, N. Ogawa, A. Ueda, H. Mori, M. Kawasaki, and Y. Tokura.:
“Phase-change memory function of correlated electrons in organic conductors”
Phys. Rev. B 91, 041101(R) (2015)
10.F. Kagawa, S. Horiuchi, N. Minami, S. Ishibashi, K. Kobayashi, R. Kumai, Y. Murakami, and Y. Tokura.:
“Polarization Switching Ability Dependent on Multidomain Topology in a Uniaxial Organic Ferroelectric”
Nano Lett. 14, 239 (2014)

Recent Research Results

Dec. 28, 2018
Rapid cooling reveals superpowers
Oct. 21, 2016
‘Snap freezing’ produces different state

Lab Members

Principal investigator

Fumitaka Kagawa: Unit Leader

Core members

Takuro Sato: Postdoctoral Researcher
Keisuke Matsuura: Special Postdoctoral Researcher
Hiroshi Oike: Visiting Scientist

Contact Information

209 Frontier Research Laboratory
2-1 Hirosawa,
Wako, Saitama
351-0198, Japan
Email: fumitaka.kagawa [at] riken.jp