skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in WSe 2/CrI 3 Heterostructures

Abstract

Monolayer valley semiconductors, such as tungsten diselenide (WSe 2), possess valley pseudospin degrees of freedom that are optically addressable but degenerate in energy. Lifting the energy degeneracy by breaking time-reversal symmetry is vital for valley manipulation. This has been realized by directly applying magnetic fields or via pseudomagnetic fields generated by intense circularly polarized optical pulses. However, sweeping large magnetic fields is impractical for devices, and the pseudomagnetic fields are only effective in the presence of ultrafast laser pulses. The recent rise of two-dimensional (2D) magnets unlocks new approaches to controlling valley physics via van der Waals heterostructure engineering. Here, we demonstrate the wide continuous tuning of the valley polarization and valley Zeeman splitting with small changes in the laser-excitation power in heterostructures formed by monolayer WSe 2 and 2D magnetic chromium triiodide (CrI 3). The valley manipulation is realized via the optical control of the CrI 3 magnetization, which tunes the magnetic exchange field over a range of 20 T. Lastly, our results reveal a convenient new path toward the optical control of valley pseudospins and van der Waals magnetic heterostructures.

Authors:
ORCiD logo [1];  [1];  [1];  [1];  [1];  [2];  [2];  [3];  [4]; ORCiD logo [5];  [1];  [1]
  1. Univ. of Washington, Seattle, WA (United States)
  2. National Institute for Materials Science, Tsukuba (Japan)
  3. Univ. of Hong Kong, Hong Kong (China)
  4. Carnegie Mellon Univ., Pittsburgh, PA (United States)
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1482455
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Nano Letters
Additional Journal Information:
Journal Volume: 18; Journal Issue: 6; Journal ID: ISSN 1530-6984
Publisher:
American Chemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 2D magnets; Magnetic proximity effect; transition-metal dichalcogenide; valley; van der Waals heterostructure

Citation Formats

Seyler, Kyle L., Zhong, Ding, Huang, Bevin, Linpeng, Xiayu, Wilson, Nathan P., Taniguchi, Takashi, Watanabe, Kenji, Yao, Wang, Xiao, Di, McGuire, Michael A., Fu, Kai-Mei C., and Xu, Xiaodong. Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in WSe2/CrI3 Heterostructures. United States: N. p., 2018. Web. doi:10.1021/acs.nanolett.8b01105.
Seyler, Kyle L., Zhong, Ding, Huang, Bevin, Linpeng, Xiayu, Wilson, Nathan P., Taniguchi, Takashi, Watanabe, Kenji, Yao, Wang, Xiao, Di, McGuire, Michael A., Fu, Kai-Mei C., & Xu, Xiaodong. Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in WSe2/CrI3 Heterostructures. United States. doi:10.1021/acs.nanolett.8b01105.
Seyler, Kyle L., Zhong, Ding, Huang, Bevin, Linpeng, Xiayu, Wilson, Nathan P., Taniguchi, Takashi, Watanabe, Kenji, Yao, Wang, Xiao, Di, McGuire, Michael A., Fu, Kai-Mei C., and Xu, Xiaodong. Mon . "Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in WSe2/CrI3 Heterostructures". United States. doi:10.1021/acs.nanolett.8b01105. https://www.osti.gov/servlets/purl/1482455.
@article{osti_1482455,
title = {Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in WSe2/CrI3 Heterostructures},
author = {Seyler, Kyle L. and Zhong, Ding and Huang, Bevin and Linpeng, Xiayu and Wilson, Nathan P. and Taniguchi, Takashi and Watanabe, Kenji and Yao, Wang and Xiao, Di and McGuire, Michael A. and Fu, Kai-Mei C. and Xu, Xiaodong},
abstractNote = {Monolayer valley semiconductors, such as tungsten diselenide (WSe2), possess valley pseudospin degrees of freedom that are optically addressable but degenerate in energy. Lifting the energy degeneracy by breaking time-reversal symmetry is vital for valley manipulation. This has been realized by directly applying magnetic fields or via pseudomagnetic fields generated by intense circularly polarized optical pulses. However, sweeping large magnetic fields is impractical for devices, and the pseudomagnetic fields are only effective in the presence of ultrafast laser pulses. The recent rise of two-dimensional (2D) magnets unlocks new approaches to controlling valley physics via van der Waals heterostructure engineering. Here, we demonstrate the wide continuous tuning of the valley polarization and valley Zeeman splitting with small changes in the laser-excitation power in heterostructures formed by monolayer WSe2 and 2D magnetic chromium triiodide (CrI3). The valley manipulation is realized via the optical control of the CrI3 magnetization, which tunes the magnetic exchange field over a range of 20 T. Lastly, our results reveal a convenient new path toward the optical control of valley pseudospins and van der Waals magnetic heterostructures.},
doi = {10.1021/acs.nanolett.8b01105},
journal = {Nano Letters},
number = 6,
volume = 18,
place = {United States},
year = {2018},
month = {5}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 28 works
Citation information provided by
Web of Science

Figures / Tables:

Figure 1 Figure 1: Basic characterization and domains of WSe2/CrI3 heterostructure. (a) Schematic of WSe2/CrI3 heterostructure (left). Valley energy level diagram and optical selection rules of monolayer WSe2 with magnetic exchange field coupling (right). h-BN encapsulation layers are not shown. (b) Optical microscope image of heterostructure. Dashed box region shows the lasermore » scanning area and the dotted yellow curve outlines the WSe2 monolayer region. Scale bar, 5 μm. (c) Spatial map of total photoluminescence (PL) intensity within the boxed region of Fig. 1b. Scale bar, 2 μm. (d) Spatial maps of the polarization parameter ρ (see text for definition) at 1 T (right) and 0.7 T (left) applied magnetic field. Same spatial scale as Fig. 1c. (e) Spectra of 𝜎+ (𝜎) PL under 𝜎+ (𝜎) laser excitation taken at 1 T applied magnetic field, shown in red (blue). (f) Magnetic field dependence of ρ for up (orange) and down (green) field sweep directions. The data was taken on domain A at the location marked by the solid purple circle in Fig. 1d. The corresponding data for domain B (marked by dashed yellow circle) is in Section S1.« less

Save / Share:

Works referencing / citing this record:

Biaxial strain effect on the electronic structure and valleytronic properties of a MoS 2 /CoO(111) heterostructure
journal, January 2019

  • Yang, Guang; Li, Jia; Liu, Ze
  • Physical Chemistry Chemical Physics, Vol. 21, Issue 27
  • DOI: 10.1039/c9cp02404b

    Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.