Studying Ferromagnetic Domains of Cobalt Ultra Thinfilm Covered on Monolayer MoS₂ by X-ray Photoemission Electron Microscopy
Chun-I Lu1*, Chih-Heng Huang2, Kun-Ta Lu1, Tzu-Hung Chuang1, Kai-Shin Li3, Yann-Wen Lan4, Der-Hsin Wei1
1Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
2Program for Synchrotron Radiation and Neutron Beam Applications, National Sun Yat-sen University, Kaohsiung, Taiwan
3National Nano Device Laboratories, National Applied Research Laboratories, Hsinchu, Taiwan
4Department of Physics, National Taiwan Normal University, Taipei, Taiwan
* Presenter:Chun-I Lu,
MoS₂, a typical 2D material of the family of transition metal dichalcogenides (TMDCs), has been demonstrated a widely application, including the spintronics: ferromagnetic (FM) materials/MoS₂ spinvalve devices [1]. On the other hand, a direct observation of the insight of such interface could help us to understand the interaction of such heterojunction and to refine the device in advance. We focus on visualizing the ferromagnetic domains of the Co thinfilm, which was deposited by molecular beam epitaxy on monolayer MoS₂ in an ultra-high vacuum environment. A series of different thickness of Co were prepared at the end-station and investigated by X-ray photoemission electron microcopy (XPEEM) at Taiwan Light Source BL05B2 in situ. We confirm the X-ray magnetic circular dichroism (XMCD) signals when the thickness is larger than 5 ML. Furthermore, the XMCD mappings indicate that, the ferromagnetism only exists at the region of Co/MoS₂, but not the region of Co on SiO₂. The magnetic domains’ shape seems to have the tendency of the thickness-invariance and preferred directions.

[1] Weiyi Wang, A. Narayan, L. Tang, K. Dolui, Y. Liu, X. Yuan, Y. Jin, Y. Wu, I. Rugger, S. Sanvito, and Faxian Xiu, Nano Lett. 15, 5261 (2015).

This project is financially sponsored by Ministry of Science and Technology of Taiwan (MOST 104-2112-M-213-002-MY3).

Keywords: MoS2, Cobalt, Magnetic Domains, XPEEM, XMCD