Diverse Structures and Magnetic Properties in Nonlayered Monolayer Chromium Selenide

Meizhuang Liu; Yu Li Huang; Jian Gou; Qijie Liang; Rebekah Chua; Arramel; Sisheng Duan; Lei Zhang; LiangLiang Cai; Xiaojiang Yu; Dingyong Zhong; Wenjing Zhang; Andrew T S Wee

doi:10.1021/acs.jpclett.1c01493

Diverse Structures and Magnetic Properties in Nonlayered Monolayer Chromium Selenide

J Phys Chem Lett. 2021 Aug 19;12(32):7752-7760. doi: 10.1021/acs.jpclett.1c01493. Epub 2021 Aug 9.

Authors

Meizhuang Liu^{1

2}, Yu Li Huang^{2

3}, Jian Gou², Qijie Liang², Rebekah Chua², Arramel², Sisheng Duan², Lei Zhang², LiangLiang Cai², Xiaojiang Yu⁴, Dingyong Zhong⁵, Wenjing Zhang¹, Andrew T S Wee²

Affiliations

¹ SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China.
² Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117551, Singapore.
³ Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Fuzhou 350207, China.
⁴ Singapore Synchrotron Light Source (SSLS), National University of Singapore, 5 Research Link, Singapore 117603, Singapore.
⁵ School of Physics and State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275, China.

PMID: 34369783
DOI: 10.1021/acs.jpclett.1c01493

Abstract

Thickness-dependent magnetic behavior has previously been observed in chemical vapor deposition-grown chromium selenide. However, the low-dimensional structure in nonlayered chromium selenide, which plays a crucial role in determining the low-dimensional magnetic order, needs further study. Here, we report the structure-dependent magnetic properties in monolayer CrSe₂ and Cr₂Se₃ grown by molecular beam epitaxy. In the monolayer CrSe₂, 1T-CrSe₂ with a lattice constant of 3.3 Å has a metallic character, coexisting with the 1T″ phase with 2 × 2 surface periodicity. Monolayer CrSe₂ can be transformed into Cr₂Se₃ with a lattice constant of 3.6 Å by annealing at 300 °C. X-ray magnetic circular dichroism (XMCD) measurements combined with DFT calculations reveal that while the MBE-grown monolayer CrSe₂ is antiferromagnetic, monolayer Cr₂Se₃ is ferromagnetic with a Curie temperature of ∼200 K. This work demonstrates the structural diversity in nonlayered chromium selenide and the critical effect of different structures on its electronic and magnetic properties.