양자물질초전도연구실에서 미국 로스알라모스 국립연구소에 스태프로 재직중인 Shizeng Lin 박사님을 초청하여 아래와 같이 세미나를 개최합니다.

학과 구성원 여러분의 많은 참석을 부탁 드립니다.

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○ Date/time: 2019. 09. 17(Tue.) 16:00

○ Place: Creative Room on 7th Floor of Samsung Library

○ Speaker: Dr. Shizeng Lin (Los Alamos National Laboratory)

○ Title: Dynamics of multiple-Q spin textures and its effect on electronic state

○ Abstract: Multiple-Q spin textures, such as magnetic bubble and skyrmion lattices, have been observed in a large family of magnets. These spin textures can be driven into motion by external stimuli. In this talk, first, I will give an overview about the spin textures in magnets. I will also discuss the dynamics of the spin texture under various drives such as electric current/thermal gradient.  The main part of the talk will focus on the effect of the motion of spin textures on the electronic states. We show that to describe correctly the electronic dynamics, the momentum space needs to be transcended to higher dimensions by including the ancillary dimensions associated with phason modes of the translational motion of the spin textures. The electronic states have non-trivial topology characterized by the first and second Chern numbers in the high dimensional hybrid momentum space. This gives rise to an anomalous electric charge transport due to the motion of spin textures. By deforming the spin textures, a nonlinear response associated with the second Chern number can be induced and results in the piezoelectricity. The charge transport is derived from the semi-classical equation of motion of electrons that depends on the Berry curvature in the hybrid momentum space. Our results suggest that the motion of multiple-Q spin textures has significant effects on the electronic dynamics and provides a new platform to explore high dimensional topological physics.

References:
1) Lin et al., Phys. Rev. Lett. 112, 187203 (2014)
2) Lin and Hayami, Phys. Rev. B 93, 064430 (2016)
3) Lin and Batista, Phys. Rev. Lett. 120, 077202 (2018)
4) Su, Hayami and Lin, arXiv:1904.05473 (2019)