Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in WSe/CrI Heterostructures.
Kyle L Seyler, Ding Zhong, Bevin Huang, Xiayu Linpeng, Nathan P Wilson, Takashi Taniguchi, Kenji Watanabe, Wang Yao, Di Xiao, Michael A McGuire, Kai-Mei C Fu, Xiaodong Xu
Author Information
Takashi Taniguchi: National Institute for Materials Science , 1-1 Namiki , Tsukuba 305-0044 , Japan.
Kenji Watanabe: National Institute for Materials Science , 1-1 Namiki , Tsukuba 305-0044 , Japan.
Wang Yao: Department of Physics and Center of Theoretical and Computational Physics , University of Hong Kong , Hong Kong , China.
Di Xiao: Department of Physics , Carnegie Mellon University , Pittsburgh , Pennsylvania 15213 , United States.
Michael A McGuire: Materials Science and Technology Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , United States. ORCID
Monolayer valley semiconductors, such as tungsten diselenide (WSe), 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 and 2D magnetic chromium triiodide (CrI). The valley manipulation is realized via the optical control of the CrI magnetization, which tunes the magnetic exchange field over a range of 20 T. Our results reveal a convenient new path toward the optical control of valley pseudospins and van der Waals magnetic heterostructures.
