Seminar : Analysis on Symmetry and Anti-symmetry in Chiral Domain-Wall Speed and Related Phenomena

Event Details

On May, 10 2017, we have the pleasure to welcome Daeyun KIM from Seoul National University (SNU) in Spintec. At 11H, he will give a seminar on “Analysis on Symmetry and Anti-symmetry inChiral Domain-Wall Speed and Related Phenomena”.

Dae-Yun Kim, Min-Ho Park, Yong-Keun Park, Joon-Moon, Joo-Sung Kim, Yune-Seok Nam, Hyun-Seok Hwang, Duck-Ho Kim, Soong-Geun Je, Byoung-Chul Min, and Sug-Bong Choe

The Dzyaloshinskii-Moriya interaction (DMI) has been attracted a great attention due to its crucial role in spintronics such as formation of chiral domain-walls (DWs) or magnetic skyrmions. Therefore, various DMI-determinationtechniques have been suggested by utilizing itscharacteristics.Among them, one of the most widely-appliedtechnique is the measurement of the DW speed as a function of anin-plane magnetic field, of which key point is analyzing thesymmetry of the DW speed variation. With the same key point, our group reported more simple version of this measurement techniques,which enables the determination of DW types (either Bloch type or Néeltype) by observing domain expansion patterns. The details of this technique will be introducedat the beginning of the presentation.
Recently, many other groups have subsequently reported the existence of the additional asymmetry in the DW speed variation, which implies the existence of new chiral phenomena such as chiral damping. To analyze the additional asymmetry, our group carefully eliminatedthesymmetric contribution (related to the DW energy density)from the DW speed variation,and extracted thepureadditional contribution. The extracted additional contribution exhibits clear antisymmetric nature in logarithmic scaleof the DW speed, and thus ourgroup speculated that the origin of the anti-symmetry comes from the exponent part of the creep scaling law. To demonstrate the origin of the anti-symmetry, the variation of the DW width as a function of an in-plane magnetic field was investigated.In the presentation, our experimental procedures and the detailedanalysis on the DW speed will be discussed. Moreover, at the last part of the presentation, our recent observation on the DW tilting will also be discussed, since its origin was found to berelated tothe symmetric and anti-symmetric contribution in chiral DW speed.

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