Highly Anisotropic Excitons and Multiple Phonon Bound States in a Van der Waals Antiferromagnetic Insulator

Abstract

Two-dimensional semiconducting systems, such as quantum wells and transition metal dichalcogenides, are the foundations to investigate low dimensional light-matter interactions. To date, the study of elementary photoexcitation, namely the exciton, in 2D semiconductors with intrinsic magnetic order remains a challenge due to the lack of suitable material platforms. Here, we report an observation of excitons coupled to zigzag antiferromagnetic order in the layered antiferromagnetic insulator NiPS3 using both photoluminescence (PL) and optical reflection spectroscopy. The exciton exhibits a linewidth as narrow as ~350 ueV with near unity linear polarization in the PL spectrum. As the thicknesses of samples is reduced from five layers to bilayers, the PL intensity is drastically suppressed and eventually vanishes in monolayers, consistent with the calculated bandgap being highly indirect for both bilayer and monolayer. We observed strong linear dichroism (LD) over a broad spectra range, which shares the same optical anisotropy axis, being locked to the zigzag direction, as the exciton PL. Both LD and the degree of linear polarization in the exciton PL decrease as the temperature increases and become negligible above the Neel temperature. These observations suggest both optical quantities are probes of the symmetry breaking magnetic order parameter. In addition, a sharp resonance in the LD spectrum is observed with an energy near the exciton PL. There exist over ten exciton-A1g phonon bound states on its high energy side, which likely result from the strong modulation of the ligand-to-metal charge transfer energy by strong electron-lattice interactions. Our work establishes NiPS3 as a new 2D platform for exploring magneto-exciton physics with strong correlations, as well as a building block for 2D heterostructures for engineering physical phenomena with time reversal symmetry breaking.

to be appear in Nature Nanotechnology

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• Cavity-Enhanced Linear Dichroism in a van der Waals Antiferromagnet
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• Spin Photovoltaic Effect in Magnetic van der Waals Heterostructures
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• Progress and Prospects in Two-Dimensional Magnetism of van der Waals Materials
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• Electronic band structure changes across the antiferromagnetic phase transition of exfoliated MnPS${}_3$ probed by $\mu$-ARPES
• Ultrafast laser-induced spin-lattice dynamics in the van der Waals antiferromagnet CoPS3
• Dimensionality crossover to 2D vestigial nematicity from 3D zigzag antiferromagnetism in an XY-type honeycomb van der Waals magnet
• All van der Waals three-terminal SOT-MRAM realized by topological ferromagnet Fe3GeTe2
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• Observation of three-state nematicity and domain evolution in atomically-thin antiferromagnetic NiPS3
• Roadmap on Quantum Magnetic Materials
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• Magnetoelectric effect in van der Waals magnets
• Exciton-magnon splitting in van der Waals antiferromagnet MnPS${}_3$ unveiled by second-harmonic generation
• Identifying band structure changes of FePS3 across the antiferromagnetic phase transition
• Quantitatively predicting angle-resolved polarized Raman intensity of anisotropic layered materials
• Distinct Optical Excitation Mechanisms of a Coherent Magnon in a van der Waals Antiferromagnet
• Brightened Optical Transition as Indicator of Multiferroicity in a Layered Antiferromagnet
• Engineering of a Layered Ferromagnet via Graphitization: An Overlooked Polymorph of GdAlSi
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• Deconstruction of the anisotropic magnetic interactions from spin-entangled optical excitations in van der Waals antiferromagnets
• Revealing the Electronic Structure of van der Waals Antiferromagnetic NiPS${}_3$ through Synchrotron-Based $\mu$-ARPES and Alkali Metal Dosing
• Quantum Fluctuations in the van der Walls material $\mathrm{NiP}{\mathrm{S}}_3$
• Spin and lattice dynamics of a van der Waals antiferromagnet MnPSe${}_3$
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• Exciton-spin interactions in antiferromagnetic charge-transfer insulators
• Probing the band structure of the strongly correlated antiferromagnet NiPS3 across its phase transition
• Magnetic Field-Tunable Repulsive Exciton-Exciton Interaction in the van der Waals Antiferromagnet NiPS${}_3$
• Magnetic anisotropy and magnetic ordering of transition-metal phosphorus trisulfides
• Crystal field tuned spin-flip luminescence in NiPS3
• Ultrafast Dynamics of Spin-Orbit Entangled Excitons Coupled to Magnetic Ordering in van der Waals Antiferromagnet NiPS3