Electronic States Microscopy Research Team

Principal Investigator

PI Name Xiuzhen Yu
Degree D.Sci.
Title Team Leader
Brief Resume
1990Master, Department of Semiconductor, Faculty of Electronic Science, Jilin University
2002Technician, Tokura Spin Superstructure Project, ERATO, Japan Science and Technology Agency
2006Engineer, Advanced Electron Microscopy Group, Advanced Nano Characterization Center, NIMS
2008Doctor of Science, Department of Physics, Graduate School of Science and Faculty of Science, Tohoku University
2008Researcher, Advanced Electron Microscopy Group, Advanced Nano Characterization Center, NIMS
2010Researcher, Tokura Multiferroic Project, ERATO, Japan Science and Technology Agency
2011Postdoctoral Researcher, Quantum Science on Strong Correlation Group, Advanced Science Institute, RIKEN
2013Senior Research Scientist, Strong Correlation Physics Research Group, Strong Correlation Physics Division, RIKEN Center for Emergent Matter Science (CEMS)
2017Team Leader, Electronic States Microscopy Research Team, RIKEN CEMS (-present)

Outline

Our team is working on the real-space observation of electron structures or topological electron-spin textures (skyrmion) and their dynamics in strong-correlation systems by means of atomic-resolution electron microscopy. We will use various microscopy techniques, such as the in-situ imaging technique with a fast-speed CMOS camera, differential phase contrast microscopy, electron energy-loss spectroscopy, and energy dispersive spectroscopy, etc., to explore the electron structures and their dynamical phase transitions or phase separations owing to external stimuli. We also use these powerful tools to quantitatively characterize the nanometric magnetic and electric fields in topological matters to exploit emergent phenomena and hence their possible applications in the spintronics.

Research Fields

Physics, Engineering, Materials Sciences

Keywords

Strongly correlated electron system
Skyrmion
Lorentz microscopy
Analytical electron microscopy
High-resolution electron microscopy

Results

Real-space observations of nanometric-topological spin textures and their dynamics

The nontrivial phenomena, such as high-TC superconductivity and colossal magnetoresistance (CMR), are caused by electronic phase transitions in strongly correlated electron systems with weak external stimuli. Among them, skyrmion, i.e., nanometric topological spin textures arising from strong spin-orbit interaction are attracting much attention since they are considered to bear potential for future functional devices. In skyrmion, several hundreds of spins swirl with a unique direction and wrap a unit sphere. Particularly, skyrmion carrying a topological number can be driven by an extremely small current which is six orders of magnitudes lower than that for a drive of the domain wall in ferromagnets.

The emergent field induced by this nontrivial topological spin texture should deflect conducting electrons and hence cause novel magnetic transport phenomena such as the topological Hall effect. As a counteraction, the skyrmion Hall motion appears when the spin-polarized current traverses the skyrmion owing to spin transfer torque. By utilizing advanced microscopy techniques, we have visualized the topological spin texture of a skyrmion (Fig. 1 (a)) and a skyrmion crystal (Fig. 1 (b)) in strongly correlated systems. We have successfully demonstrated a current-driven single skyrmion motion and a current-excited topological phase transition.

(a)Topological spin textures in a skyrmion (a) and skyrmion crystal (b) realized by differential phase contrast microscopy. Colors and white arrows show the magnitude and directions of the magnetic moments in the skyrmion.

Members

Xiuzhen Yu

Team Leader yu_x[at]riken.jp R

お問い合わせ

2-1 Hirosawa, Wako, Saitama 351-0198 Japan

E-mail:
yu_x[at]riken.jp

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