Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 40: 2D Materials and Heterostructures: Magnetic Properties
HL 40.10: Vortrag
Donnerstag, 21. März 2024, 12:15–12:30, EW 201
Impact of proximity exchange coupled CrI3 on WSe2 valley dynamics — •Marc Schütte1, Jo Bertram1, Frank Volmer2, Kenji Watanabe3, Takashi Taniguchi4, Christoph Stampfer1, Lutz Waldecker1, and Bernd Beschoten1 — 12nd Institute of Physics A and JARA-FIT, RWTH Aachen University, Aachen, Germany — 2AMO GmbH, Advanced Microelectronic Center Aachen (AMICA), Aachen, Germany — 3Research Center for Functional Materials, NIMS, Tsukuba, Japan — 4International Center for Materials Nanoarchitectonics, NIMS, Tsukuba, Japan
The optical selection rules of the transition metal dichalcogenides allow to individually address and manipulate their two energetically degenerate, but distinct, valleys in k-space. Lifting the degeneracy of the valley degree of freedom is possible via magnetic proximity coupling of adjacent layered magnetic materials. Here, thin layers of the two-dimensional layer-antiferromagnet CrI3 are put into direct contact with monolayer WSe2.
We present our findings about the valley dynamics in electrostatically gated, proximity exchange coupled CrI3/WSe2 heterostructures by optical reflection spectroscopy and time-resolved Kerr measurements. In particular, we find a type-II band alignment. This leads to charge separation within the heterostructure and long-lived valley polarizations within the WSe2 valence bands. Excited polarizations furthermore show helicity dependent lifetime differences at particular gate voltages, which emerge from the modified band structure at K and K′.
Keywords: 2D magnet; Transition metal dichalcogenides; Heterostructure; Time-resolved Kerr; Valley polarization