Unveiling Extraordinary Room Temperature Ferromagnetic Behavior in Gamma ray induced and Gd-Doped few-layered MoS2 Thin Films Deposited via Magnetron Sputtering

Chih-Hao Lee^1*, Ming-Hsuan Wu¹, Fang-Chi Hu¹, Aswin kumar Anbalagan¹, Weng Kent Chan¹, Hsin-Yi Tiffany Chen¹, Chao-Chin Wang¹, Huang-Ming Tsai³, Sheng-Yun Wu²

¹Department of Engineering and System Science, National Tsing Hua University, Hsinchu, Taiwan
²Department of Physics, National Dong Hwa University, Haulian, Taiwan
³Synchrotron Radiation Research Center, Hsinchu, Taiwan

* Presenter:Chih-Hao Lee, email:chlee@mx.nthu.edu.tw

In this work, we successfully achieved the goal of large area (cm² size) inducing magnetism on diamagnetic MoS₂ 3.5 nm thin films by doping Gd atoms with concentrations of 0.36, 0.47, 1.05 and 3.3 %. For the 0.47% Gd-doped MoS₂ (few layers 3.5 nm) thin films, a remarkably higher saturation magnetization of about 454 emu/cm³ at room temperature. With gamma ray (⁶⁰Co) irradiation, the few layers MoS ₂ samples also possess 610 emu/cm³ under 9 kGy. X-ray magnetic circular dichroism on Gd and Mo atoms reveals that small portion of magnetic moments contributed from the Gd and Mo atoms alone. Defects created by either Gd dopants or gamma ray is a major factor. The DFT calculation showed the vacancy of one Mo plus two S is the major magnetization source instead of sulfur vacancies in the gamma irradiation samples. Anneal samples to reduce the defect concentration results in a significant reduction of magnetization, especially, annealed under H₂S environment. Combining the results of these characterization techniques, the bound magnetic polaron model is proposed to explain the result of ultrahigh ferromagnetism.

Keywords: MoS2, magnetization, defects, gamma ray , Gd doped