PHYSICS/BK21 SEMINAR[09.10.28]

SPIN DYNAMICS OVER WIDE TIME SCALES”

* Speaker : Prof. Dong-Hyun Kim[Chungbuk University]
* Place : Physics Seminar Room (Science Bldg, 3-201)
* Date & Time : Oct,  28(Wed)  4:00 ~ 5:00 pm
 
ABSTRACT:

On a time scale slower than μs, it has been known that spin fluctuation in ferromagnetic materials exhibits a nontrivial collective behavior, leading to an interesting statistical phenomenon of critical scaling behavior, such as Barkhausen avalanche [1,2]. In this work, spin dynamics directly observed for wide temporal ranges from ms to ps time scales by means of magnetic imaging techniques such as magneto-optical Kerr microscopy and soft X-ray microscopy will be presented. To study spin dynamics on a sub-ns time scale, we have developed an electronic pump-probe stroboscopic technique combined with the soft X-ray microscopy developed at BL 6.1.2 in ALS. Direct observation of spin dynamics, particularly of magnetic domain wall and magnetic vortex, driven by a pulsed magnetic field or a pulsed spin current in various ferromagnetic nanoelements has revealed detailed spin behaviors on a sub-ns time scale, which is compared with the micromagnetic simulation [3,4]. REFERENCES [1] D.-H. Kim, S.-B. Choe, and S.-C. Shin, Phys. Rev. Lett. 90, 87203 (2003). [2] M.-Y. Im, S.-H. Lee, D.-H. Kim, P. Fischer, and S.-C. Shin, Phys. Rev. Lett. 100, 167204 (2008). [3] G. Meier, M. Bolte, R. Eiselt, B. Kraeuger, D.-H. Kim, and P. Fischer, Phys. Rev. Lett. 98, 187202 (2007). [4] H.-G. Piao, D. Djuhana, S. K. Oh, S.-C. Yu, and D.-H. Kim, Appl. Phys. Lett. 94, 052501 (2009).

Contact Person : Prof. Dong Eon Kim (054-279-2089, kimd@postech.ac.kr)