Giant nonreciprocal second-harmonic generation from antiferromagnetic bilayer CrI3

Zeyuan Sun; Yangfan Yi; Tiancheng Song; Genevieve Clark; Bevin Huang; Yuwei Shan; Shuang Wu; Di Huang; Chunlei Gao; Zhanghai Chen; Michael McGuire; Ting Cao; Di Xiao; Wei-Tao Liu; Wang Yao; Xiaodong Xu; Shiwei Wu

doi:10.1038/s41586-019-1445-3

Giant nonreciprocal second-harmonic generation from antiferromagnetic bilayer CrI₃

Nature. 2019 Aug;572(7770):497-501. doi: 10.1038/s41586-019-1445-3. Epub 2019 Jul 31.

Authors

Zeyuan Sun^#^{1

2}, Yangfan Yi^#^{1

2}, Tiancheng Song³, Genevieve Clark⁴, Bevin Huang³, Yuwei Shan^{1

2}, Shuang Wu^{1

2}, Di Huang^{1

2}, Chunlei Gao^{1

2

5}, Zhanghai Chen^{1

2

5}, Michael McGuire⁶, Ting Cao^{4

7}, Di Xiao⁸, Wei-Tao Liu^{1

2

5}, Wang Yao⁹, Xiaodong Xu^{10

11}, Shiwei Wu^{12

13

14}

Affiliations

¹ State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai, China.
² Key Laboratory of Micro and Nano Photonic Structures (MOE), Department of Physics, Fudan University, Shanghai, China.
³ Department of Physics, University of Washington, Seattle, WA, USA.
⁴ Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA.
⁵ Collaborative Innovation Center of Advanced Microstructures, Nanjing, China.
⁶ Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
⁷ Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA, USA.
⁸ Department of Physics, Carnegie Mellon University, Pittsburgh, PA, USA.
⁹ Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China.
¹⁰ Department of Physics, University of Washington, Seattle, WA, USA. xuxd@uw.edu.
¹¹ Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA. xuxd@uw.edu.
¹² State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai, China. swwu@fudan.edu.cn.
¹³ Key Laboratory of Micro and Nano Photonic Structures (MOE), Department of Physics, Fudan University, Shanghai, China. swwu@fudan.edu.cn.
¹⁴ Collaborative Innovation Center of Advanced Microstructures, Nanjing, China. swwu@fudan.edu.cn.

^# Contributed equally.

PMID: 31367036
DOI: 10.1038/s41586-019-1445-3

Abstract

Layered antiferromagnetism is the spatial arrangement of ferromagnetic layers with antiferromagnetic interlayer coupling. The van der Waals magnet chromium triiodide (CrI₃) has been shown to be a layered antiferromagnetic insulator in its few-layer form¹, opening up opportunities for various functionalities^2-7 in electronic and optical devices. Here we report an emergent nonreciprocal second-order nonlinear optical effect in bilayer CrI₃. The observed second-harmonic generation (SHG; a nonlinear optical process that converts two photons of the same frequency into one photon of twice the fundamental frequency) is several orders of magnitude larger than known magnetization-induced SHG^8-11 and comparable to the SHG of the best (in terms of nonlinear susceptibility) two-dimensional nonlinear optical materials studied so far^12,13 (for example, molybdenum disulfide). We show that although the parent lattice of bilayer CrI₃ is centrosymmetric, and thus does not contribute to the SHG signal, the observed giant nonreciprocal SHG originates only from the layered antiferromagnetic order, which breaks both the spatial-inversion symmetry and the time-reversal symmetry. Furthermore, polarization-resolved measurements reveal underlying C_2h crystallographic symmetry-and thus monoclinic stacking order-in bilayer CrI₃, providing key structural information for the microscopic origin of layered antiferromagnetism^14-18. Our results indicate that SHG is a highly sensitive probe of subtle magnetic orders and open up possibilities for the use of two-dimensional magnets in nonlinear and nonreciprocal optical devices.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.