Evolution of interlayer and intralayer magnetism in three atomically thin chromium trihalides

Hyun Ho Kim; Bowen Yang; Siwen Li; Shengwei Jiang; Chenhao Jin; Zui Tao; George Nichols; Francois Sfigakis; Shazhou Zhong; Chenghe Li; Shangjie Tian; David G Cory; Guo-Xing Miao; Jie Shan; Kin Fai Mak; Hechang Lei; Kai Sun; Liuyan Zhao; Adam W Tsen

doi:10.1073/pnas.1902100116

Evolution of interlayer and intralayer magnetism in three atomically thin chromium trihalides

Proc Natl Acad Sci U S A. 2019 Jun 4;116(23):11131-11136. doi: 10.1073/pnas.1902100116. Epub 2019 May 20.

Authors

Hyun Ho Kim^{1

2}, Bowen Yang^{1

3}, Siwen Li⁴, Shengwei Jiang^{5

6

7}, Chenhao Jin^{5

6

7}, Zui Tao^{5

6

7}, George Nichols^{1

3}, Francois Sfigakis^{1

2}, Shazhou Zhong^{1

3}, Chenghe Li^{8

9}, Shangjie Tian^{8

9}, David G Cory^{1

2}, Guo-Xing Miao^{1

10}, Jie Shan^{5

6

7}, Kin Fai Mak^{5

6

7}, Hechang Lei^{8

9}, Kai Sun⁴, Liuyan Zhao⁴, Adam W Tsen^{11

2}

Affiliations

¹ Institute for Quantum Computing, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
² Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
³ Department of Physics and Astronomy, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
⁴ Department of Physics, University of Michigan, Ann Arbor, MI 48109.
⁵ School of Applied and Engineering Physics, Cornell University, Ithaca, NY 14853.
⁶ Department of Physics, Cornell University, Ithaca, NY 14853.
⁷ Kavli Institute at Cornell for Nanoscale Science, Cornell University, Ithaca, NY 14853.
⁸ Department of Physics, Renmin University of China, 100872 Beijing, China.
⁹ Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-Nano Devices, Renmin University of China, 100872 Beijing, China.
¹⁰ Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada.
¹¹ Institute for Quantum Computing, University of Waterloo, Waterloo, ON N2L 3G1, Canada; awtsen@uwaterloo.ca.

Abstract

We conduct a comprehensive study of three different magnetic semiconductors, CrI₃, CrBr₃, and CrCl₃, by incorporating both few-layer and bilayer samples in van der Waals tunnel junctions. We find that the interlayer magnetic ordering, exchange gap, magnetic anisotropy, and magnon excitations evolve systematically with changing halogen atom. By fitting to a spin wave theory that accounts for nearest-neighbor exchange interactions, we are able to further determine a simple spin Hamiltonian describing all three systems. These results extend the 2D magnetism platform to Ising, Heisenberg, and XY spin classes in a single material family. Using magneto-optical measurements, we additionally demonstrate that ferromagnetism can be stabilized down to monolayer in more isotropic CrBr₃, with transition temperature still close to that of the bulk.

Keywords: 2D magnetism; chromium trihalides; tunneling spectroscopy.