Realization of Robust and Ambient-Stable Room-Temperature Ferromagnetism in Wide Bandgap Semiconductor 2D Carbon Nitride Sheets

Yong Wang; Wei Xu; Lin Fu; Yu Zhang; Yizhang Wu; Liting Wu; Dingyi Yang; Shouzhong Peng; Jing Ning; Chi Zhang; Xuan Cui; Wei Zhong; Yan Liu; Qihua Xiong; Genquan Han; Yue Hao

doi:10.1021/acsami.3c11467

Realization of Robust and Ambient-Stable Room-Temperature Ferromagnetism in Wide Bandgap Semiconductor 2D Carbon Nitride Sheets

ACS Appl Mater Interfaces. 2023 Nov 29;15(47):54797-54807. doi: 10.1021/acsami.3c11467. Epub 2023 Nov 14.

Authors

Yong Wang^{1

2}, Wei Xu³, Lin Fu⁴, Yu Zhang⁵, Yizhang Wu⁶, Liting Wu^{1

2}, Dingyi Yang^{1

2}, Shouzhong Peng⁷, Jing Ning¹, Chi Zhang¹, Xuan Cui¹, Wei Zhong³, Yan Liu^{1

2}, Qihua Xiong⁸, Genquan Han^{1

2}, Yue Hao^{1

2}

Affiliations

¹ Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory, School of Microelectronics, Academy of Advanced Interdisciplinary Research, Xidian University, Xi'an 710071, China.
² Emerging Device and Chip Laboratory, Hangzhou Institute of Technology, Xidian University, Hangzhou 311200, China.
³ National Laboratory of Solid State Microstructures, Collaborative Innovation Center of Advanced Microstructures and Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University, Nanjing 210093, China.
⁴ Department of Physics, State Key Laboratory of Surface Physics and Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China.
⁵ Department of Physics, Shaanxi University of Science and Technology, Xi'an 710021, China.
⁶ Department of Applied Physical Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514, United States.
⁷ Fert Beijing Institute, Beijing Advanced Innovation Center for Big Data and Brain Computing, School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100091, China.
⁸ State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, China.

PMID: 37962367
DOI: 10.1021/acsami.3c11467

Abstract

Due to their weak intrinsic spin-orbit coupling and a distinct bandgap of 3.06 eV, 2D carbon nitride (CN) flakes are promising materials for next-generation spintronic devices. However, achieving strong room-temperature (RT) and ambient-stable ferromagnetism (FM) remains a huge challenge. Here, we demonstrate that the strong RT FM with a high Curie temperature (T_C) up to ∼400 K and saturation magnetization (M_s) of 2.91 emu/g can be achieved. Besides, the RT FM exhibits excellent air stability, with M_s remaining stable for over 6 months. Through the magneto-optic Kerr effect, Hall device, X-ray magnetic circular dichroism, and magnetic force microscopy measurements, we acquired clear evidence of magnetic behavior and magnetic domain evolutions at room temperature. Electrical and optical measurements confirm that the Co-doped CN retains its semiconductor properties. Detailed structural characterizations confirm that the single-atom Co coordination and nitrogen defects as well as C-C covalent bonds are simultaneously introduced into CN. Density functional theory calculations reveal that introducing C-C bonds causes carrier spin polarization, and spin-polarized carrier-mediated magnetic exchange between adjacent Co atoms leads to long-range magnetic ordering in CN. We believe that our findings provide a strong experimental foundation for the enormous potential of 2D wide bandgap semiconductor spintronic devices.

Keywords: 2D carbon nitride sheets; DFT calculations; room-temperature ferromagnetism; spintronics materials; wide bandgap semiconductor.