Ultrafast Light-Induced Magnetoelectric Effect in van der Waals Magnetic Semiconductor Heterostructures
Wenyi Zhou, Ravi Kumar Bandapelli, Hari Paudyal, Bangzheng Han, I-Hsuan Kao + 6 more
TLDR
This paper demonstrates an ultrafast light-induced magnetoelectric effect in WS₂/CrGeTe₃ heterostructures, driven by charge transfer and spin currents.
Key contributions
- Ultrafast optical excitation of WS₂/CrGeTe₃ bilayers produces an opposite sign of magnetic torque.
- The mechanism involves photoexcited carrier charge transfer across the interface, altering perpendicular magnetic anisotropy.
- Optically-generated spin currents from WS₂ into CGT also trigger precessional dynamics via angular momentum transfer.
- Results are supported by time-resolved magneto-optic Kerr effect, DFT, and Landau-Lifshitz-Gilbert simulations.
Why it matters
This research unveils a novel ultrafast light-induced magnetoelectric effect in van der Waals heterostructures. Understanding these mechanisms, driven by charge transfer and spin currents, opens new avenues for manipulating magnetization. This could lead to advanced spintronic devices and energy-efficient data storage.
Original Abstract
Atomic-scale heterostructures of van der Waals (vdW) magnets and semiconductors provide a unique environment for exploring magnetic dynamics. In contrast to typical photothermal excitation of precessional magnetization dynamics by a pump laser pulse, we find that ultrafast optical excitation of a WS$_2$/CrGeTe$_3$ (CGT) bilayer produces an opposite sign of magnetic torque compared to an isolated CGT film. Experimental observations by time-resolved magneto-optic Kerr effect (TR-MOKE) and theoretical analysis by density functional theory (DFT) and Landau-Lifshitz-Gilbert (LLG) simulations support a mechanism in which charge transfer of photoexcited carriers across the interface alters the perpendicular magnetic anisotropy, which in turn generates a torque on the magnetic layer to trigger precessional magnetization dynamics. These results provide new avenues for ultrafast manipulation of magnetization in vdW heterostructures with type-II band alignments. Lastly, we show that optically-generated spin currents from WS$_2$ into CGT can also trigger precessional dynamics via angular momentum transfer.
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