Young CALDES Members

Board

Seonghoon Woo

December 1(Fri) - December 1(Fri), 2017

Electrical control of topological spin textures for the next generation spintronic devices

Seonghoon Woo

Center for Spintronics, Korea Institute of Science and Technology (KIST)

In spintronics-based technologies, the electron spin, not the electron charge, carries the

information. In the last few years, in particular, we have seen that non-uniform topological magnetic

configurations, such as spin waves (SWs), magnetic domain walls (DWs), and chiral magnetic

configurations such as magnetic skyrmions, can be stabilized, manipulated, and controlled electrically,

and could thus potentially be exploited to store, process, and transmit data at high speed with almost

negligible power cost. In this talk, based on our recent observations, I will discuss how to efficiently

generate and manipulate these non-uniform spin disturbances in nanoscale material systems.

First, the efficient electrical manipulation of gigahertz SWs in a nanoscale magnetic device will be

discussed. [1, 2] In particular, I will demonstrate that DW annihilation can be used as a means to

generate localized, energetic SW bursts, whose interactions with a nearby DW can be probed through the

influence on field-driven depinning. We find that propagating SWs exert a force on a stationary DW that

can aid in its depinning. These results provide the first experimental evidence that SWs can significantly

affect DW dynamics and demonstrate that DWs can be used as both a source and detector of SWs in

nanoscale magnetic devices. [1]

Second, I will present our recent achievements in the field of room-temperature skyrmionics. [3-6]

Magnetic skyrmions are topologically protected exotic spin textures that exhibit fascinating physical

behaviors and have considerable potential as the basis for highly energy-efficient data storage and logic

device applications. I will first demonstrate that stable magnetic skyrmion state can be stabilized and

electrically controlled in metallic ferromagnets at room temperature. [3] I will also present the

nanosecond-dynamics of a 100 nm-size ferromagnetic skyrmion during a current pulse application. [4]

Furthermore, our recent discovery of a new type of skyrmion, called ferrimagnetic skyrmion, will be

discussed. In this work, we present the stabilization of such skyrmions and their current-driven dynamics

in ferrimagnetic films. [5] Lastly, I will present the electrical creation and annihilation of a single magnetic

skyrmion at room temperature, which are essential prerequisites for device application but have remained

elusive so far. [6] Together, our discoveries provide important technological advances towards the

realization of fully functional skyrmion-based devices

[1] S. Woo et al., Nat. Phys. 13, 448–454 (2017)

[2] S. Woo et al., J. Appl. Phys. 122, 93901 (2017)

[3] S. Woo et al., Nat. Mater. 15, 501-506 (2016)

[4] S. Woo et al., Nat. Commun. 8, 15573 (2017)

[5-6] S. Woo et al., submitted. arXiv:170310310 & S. Woo et al., submitted. arXiv:170606726