Real-time observation of magnetization and magnon dynamics in a two-dimensional topological antiferromagnet MnBi2Te4

Abstract

Atomically thin van der Waals magnetic materials have not only provided a fertile playground to explore basic physics in the two-dimensional (2D) limit but also created vast opportunities for novel ultrafast functional devices. Here we systematically investigate ultrafast magnetization dynamics and spin wave dynamics in few-layer topological antiferromagnetic MnBi2Te4 crystals as a function of layer number, temperature, and magnetic field. We find laser-induced (de)magnetization processes can be used to accurately track the distinct magnetic states in different magnetic field regimes, including showing clear odd-even layer number effects. In addition, strongly field-dependent antiferromagnetic magnon modes with tens of gigahertz frequencies are optically generated and directly observed in the time domain. Remarkably, we find that magnetization and magnon dynamics can be observed in not only the time-resolved magneto-optical Kerr effect but also the time resolved reflectivity, indicating strong correlation between the magnetic state and electronic structure. These measurements present the first comprehensive overview of ultrafast spin dynamics in this novel 2D antiferromagnet, paving the way for potential applications in 2D antiferromagnetic spintronics and magnonics as well as further studies of ultrafast control of both magnetization and topological quantum states.

References in corpus (14)

• Topological Field Theory of Time-Reversal Invariant Insulators
• Magnetic 2D materials and heterostructures
• Ising-Type Magnetic Ordering in Atomically Thin FePS3
• Antiferromagnetic topological insulators
• Exciton-Coupled Coherent Magnons in a 2D Semiconductor
• Intertwined Topological and Magnetic Orders in Atomically Thin Chern Insulator MnBi2Te4
• Optical Stabilization of Fluctuating High Temperature Ferromagnetism in YTiO${}_3$
• Robust A-type order and spin-flop transition on the surface of the antiferromagnetic topological insulator MnBi${}_2$Te${}_4$
• Axion optical induction of antiferromagnetic order
• Coherent Helicity-Dependent Spin-Phonon Oscillations in the Ferromagnetic van der Waals Crystal CrI3
• Theory of optical axion electrodynamics and application to the Kerr effect in topological antiferromagnets
• Ultrafast coherent interlayer phonon dynamics in atomically thin layers of MnBi2Te4
• Large Itinerant Electron Exchange Coupling in the Magnetic Topological Insulator MnBi2Te4
• Influence of magnetic ordering on the optical response of the antiferromagnetic topological insulator MnBi${}_2$Te${}_4$

Cited by in corpus (5)

• Observation of the Axion quasiparticle in 2D MnBi${}_2$Te${}_4$
• Antiferromagnetic Quantum Anomalous Hall Effect Modulated by Spin Flips and Flops
• Discovery of terahertz-frequency orbitally-coupled magnons in a kagome ferromagnet
• Strongly enhanced topological quantum phases in dual-surface AlO${}_x$-encapsulated MnBi${}_2$Te${}_4$
• Research on topological materials using ultrafast spectroscopy