Spin-Orbit Technologies: From Magnetic Memory to Terahertz Generation
CIC nanoGUNE Seminars
- Speaker
-
Hyunsoo Yang, National University of Singapore
- When
-
2019/10/17
13:00 - Place
- nanoGUNE seminar room, Tolosa Hiribidea 76, Donostia - San Sebastian
- Add to calendar
- iCal
Spintronic devices utilize an electric current to alter the state of a
magnetic material and thus find great applications in magnetic memory. Over
the last decade, spintronic research has focused largely on techniques based
on spin-orbit coupling, such as spin-orbit torques (SOTs), to alter the
magnetic state. The phenomenon of spin-orbit coupling in magnetic
heterostructures was also recently used to generate terahertz emission and
thus bridge the gap between spintronics and optoelectronics research.
I will introduce the basic concepts of SOTs, such as their physical origin,
the effect of SOTs on a magnetic material, and how to quantitatively measure
this effect [1,2]. Next, I will discuss the latest trends in SOT research,
such as the exploration of novel material systems like topological insulators
and two-dimensional materials to improve the operation efficiency [2,3].
Following this, some of the technical challenges in SOT-based magnetic memory
will be highlighted [3]. Moving forward, I will introduce the process of
terahertz generation in magnetic heterostructures [4], where the spin-orbit
coupling phenomenon plays a dominant role. I will discuss the details of how
this terahertz emission process can be extended to novel material systems such
as ferrimagnets [5], topological materials [6], and 2D materials. The final
section will focus on how the terahertz generation process can be used to
measure SOTs in magnetic heterostructures, thus highlighting the interrelation
between terahertz generation and the SOTs, which are linked by the underlying
spin-orbit coupling.
[1] X. Qiu et al., “Characterization and manipulation of spin orbit torque
in magnetic heterostructures,†_Adv. Mater._ , **30** , 1705699 (2018).
[2] Y. Wang et al., “FMR-related phenomena in spintronic devices†_J.
Phys. D: Appl. Phys._ , **51** , 273002 (2018).
[3] R. Ramaswamy et al., “Recent advances in spin-orbit torques: Moving
towards device applications†_Appl. Phys. Rev_., **5** , 031107 (2018).
[4] Y. Wu et al., “High-performance THz emitters based on
ferromagnetic/nonmagnetic heterostructures†_Adv. Mater._ , **29** , 1603031
(2017).
[5] M. Chen, et al., “Terahertz emission from compensated magnetic
heterostructures,†_Adv. Opt. Mater_., **6** , 1800430 (2018).
[6] X. Wang, et al., “Ultrafast Spin-To-Charge Conversion at the Surface of
Topological Insulator Thin Films†_Adv. Mat._ **30** , 1802356 (2018).
[7] L. Cheng, et al., “Far out-of-equilibrium spin populations trigger
giant spin injection into atomically thin MoS2†_Nat. Phys._ **15** , 347
(2019)
**Hyunsoo Yang** obtained the bachelor’s degree from Seoul National
University and the PhD degree from Stanford University. He worked at C&S
Technology, Seoul; LG Electronics, San Jose, CA; and Intelligent Fiber Optic
Systems, Sunnyvale, CA, USA. From 2004 to 2007, he was at the IBM-Stanford
Spintronic Science and Applications Center, IBM Almaden Research Center. He is
currently a GlobalFoundries Chaired Professor in the Department of Electrical
and Computer Engineering, National University of Singapore, working on various
magnetic materials and devices for spintronics applications. He has authored
180 journal articles, given 110 invited presentations, and holds 15 patents.
Prof. Yang was a recipient of the Outstanding Dissertation Award for 2006 from
the American Physical Society (GMAG) and IEEE Distinguished Lecturer of
Magnetic Society for 2019.
**Host:** F. Casanova