Special seminar in Dept. of Physics

2020.Nov.19.

1. 연사: 양시훈
박사 (IBM Research)

2. 일시: 2020. 11. 24(화), 오후 1시~2시 온라인(zoom)

3. zoom ID: 832 4225 1526, 비번: 2713, 회의참가 URL: https://us02web.zoom.us/j/83242251526

4. 제목:
Spin current, chirality, topological excitations, and broken symmetries in
nanostructures

Spin current acts as a key player in quantum spintronics
attracting enormous attention from chemistry and even biology as well as other
communities of condensed matter physics these days.  Since spin is a
relativistic quantum mechanical attribute, it can be coupled to a transverse
electric field through spin-orbit interaction thus acquiring chirality in
various broken symmetry systems.  As the chiral spin travels through
chiral nanostructures that have broken inversion or mirror symmetry, the moving
spin gets polarized.  This is called chiral induced spin selectivity
(CISS) [1] that serves as an underlying mechanism in chiral molecule
spintronics exhibiting numerous intriguing phenomena and potential applications
[2].  On the other hand, the spin current can actively influence
topological chiral excitations like magnetic domain walls in inversion symmetry
broken magnetic nanostructures in the form of emergent torque and phenomena
such as chiral spin-orbit torque [3], exchange coupling torque [4], and chiral
exchange drag [5].  Note that the spin current gets effectively relaxed
through various dissipation channels, particularly, spin-pumping at the interfaces
with heavy metals or even superconductors in an exotic manner [6].  In
this seminar, I will talk about the recent advances in the vibrant studies on “Spin Current” from broken mirror/inversion
and time-reversal symmetries providing the outlook of potential applications
with new functionalities.  In the end of the talk, I will present my
detailed research topics, plans, roadmaps, and vision.

[1]
Oren Ben Dor et al, Nature Communications 8, 14567 (2017).

[2] K.
Banerjee-Ghosh et al, Science 360, 1331 (2018).

[3]
K.-S. Ryu, L. Thomas, S.-H. Yang, and S. S. P. Parkin, Nature Nanotechnology 8,
527 (2013).

[4]
S.-H. Yang, K.-S. Ryu, and S. S. P. Parkin, Nature Nanotechnology 10, 221
(2015).

[5]
S.-H. Yang, C. Garg, and S. S. P. Parkin, Nature Physics 15, 543 (2019).

[6] Y.
Yao, R. Cai, T. Yu, Y. Tsutsumi, Y. Ma, W. Xing, Y. Ji,  X.-C. Xie, S.-H.
Yang, S. Maekawa, and W. Han, submitted.