Soliton-like Magnetic Domain Wall Motion Induced by the Interfacial Dzyaloshinskii-Moriya Interaction

Published in “Nature Physics”(Online Publication, November 9, 2015).

Mr. Tono, T., Assist Prof. Moriyama, T., Prof. Ono. T., Mr. Taniguchi, T., Ms. Yoshimura, Y., Assist Prof. Kim, K.J. (clockwise from the one on the far left)

Prof. Ono. T.; Assist Prof. Kim, K.J.; Assist Prof. Moriyama, T.; Ms. Yoshimura, Y.; Mr. Taniguchi, T.; Mr. Tono, T.; Dr. Ueda, K.1; Dr. Hiramatsu, R.2
(Nanospintronics, Division of Materials Chemistry)
(1:presently, PD of Massachusetts Institute of Technology)
(2:presently, PD of National Institute of Advanced Industrial Science and Technology)

 

Prof. Nakatani, Y.; Mr. Yamada, K.
(The University of Electro-Communications)                                 

 

With the advance of nanotechnology, the device architecture continues to shrink down to the regime where the interfacial effect becomes dominant rather than the bulk effect. Thus, it is important to understand the underlying mechanism that governs the phenomena in such a low dimensional system. In this work, we investigated the magnetic-field driven domain wall (DW) dynamics in a two dimensional system where the interfacial effect emerges and governs the dynamics. We found that the DW velocity becomes much faster in the presence of interfacial effect. Furthermore, the DW velocity is found to maintain constant in a wide range of magnetic field. By comparing with simulation result, we found that such a distinct DW velocity is caused by the novel interfacial effect named as interfacial Dzyaloshinskii-Moriya interaction which makes the DW as a topologically protected soliton-like object. Our results therefore elucidated the fundamental mechanism of DW dynamics in the presence interfacial effect, which is an important step forward to fully understanding of magnetic DW dynamics.

Figure.Schematic illustration of conventional DW dynamics and newly found DW dynamics. (left side) Conventional DW dynamics DW velocity increases with field up to Walker field, beyond which it abruptly decreases. First regime corresponds to the steady regime of DW and the second regime corresponds to the precessional regime of DW. (right side) Newly found DW dynamics In the presence of interfacial effect in 2 dimensional system, precessional motion is completely suppressed and DW moves with constant speed even above the Walker field.

 

Domain wall (DW): The boundary between two different magnetic domains in ferromagnet.

 

Interfacial Dzyaloshinskii–Moriya interaction (DMI): DMI is a second order of exchange interaction and is significant only at interface or surface where the structure inversion symmetry is broken. The DMI prefers a chiral spin structure.

 

This work was supported by a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) through the JSPS and the JURC at ICR, Kyoto University.

 

Yoshimura, Y.; Kim, K.J.; Taniguchi, T.; Tono, T.; Ueda, K.; Hiramatsu, R.; Moriyama, T.; Yamada, K.; Nakatani, Y.; Ono. T., Soliton-like Magnetic Domain Wall Motion Induced by the Interfacial Dzyaloshinskii-Moriya Interaction, Nature Physics, doi:10.1038/nphys3535 (2015).