Coherent strong-coupling of terahertz magnons and phonons in a Van der Waals antiferromagnetic insulator

Zhang, Q.; Ozerov, Mykhaylo; Boström, Emil Viñas; Cui, Jianying; Suri, Nishchay; Jiang, Qianni; Wang, C.; Wu, Fan; Hwangbo, Kyle; Chu, J.-H.; Rubio, Ángel; Xu, Xiaodong

doi:10.48550/arxiv.2108.11619

Cited by 8 publications

(18 citation statements)

References 37 publications

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“…A. Pressure induced magnon-polarons Magnon-polarons have recently been evidenced in bulk FePS 3 by magneto-Raman scattering and infrared spectroscopy techniques [15][16][17]. The strong coupling between magnons and phonons affects the energies of both excitations for any energy detuning, and this effect is strongly enhanced when the energies of both excitations are resonant.…”

Section: Resultsmentioning

confidence: 99%

“…Zone-center magnon-polarons are evidenced by applying a magnetic field to change the magnon energy and to bring it in coincidence with a phonon excitation [14] while probing both phonon and magnon excitation spectra by optical means. In the case of FePS 3 , a layered antiferromagnet, a series of magnonpolarons involving the three phonon modes with energy lower than the magnon excitation, have been recently observed in high magnetic fields [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

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High pressure tuning of magnon-polarons in the layered antiferromagnet FePS$_3$

Pawbake,

Pelini,

Delhomme

et al. 2022

Preprint

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Magnetic layered materials have emerged recently as promising systems to introduce magnetism in structures based on two-dimensional (2D) materials and to investigate exotic magnetic ground states in the 2D limit. In this work, we apply high hydrostatic pressures up to P ∼ 8.7 GPa to the bulk layered antiferromagnet FePS3 to tune the collective lattice excitations (phonons) in resonance with magnetic excitations (magnons). Close to P = 4 GPa, the magnon-phonon resonance is achieved and the strong coupling between these collective modes leads to the formation of new quasi-particles, the magnon-polarons, evidenced in our low temperature Raman scattering experiments by a particular avoided crossing behavior between the phonon and the doubly degenerate antiferromagnetic magnon. At the pressure-induced magnon-phonon resonance, three distinct coupled modes emerge. As it is mainly defined by intralayer properties, we show that the energy of the magnon is nearly pressure independent. We additionally apply high magnetic fields up to B = 30 T to fully identify and characterize the magnon excitations, and to explore the different magnon-polaron regimes for which the phonon has an energy lower-, equal to-, or higher-than the magnon energy. The description of our experimental data requires introducing a phonon-phonon coupling not taken into account in actual calculations.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High pressure tuning of magnon-polarons in the layered antiferromagnet FePS$_3$

Pawbake,

Pelini,

Delhomme

et al. 2022

Preprint

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“…Optically driven collective lattice mode carry therefore tremendous potential for the manipulation of the long-range magnetic order in 2D magnets, in particular considering the well-established possibility to drive such modes fully coherently even with a photon-energy far from their eigenfrequency 17,18 . In this work we experimentally investigate a flake of the van der Waals antiferromagnet FePS 3 , demonstrating the coherent laser-induced excitation of an optical lattice mode, intimately coupled to the long-range magnetic order, since it can be detected only below the ordering temperature and, additionally, it is reported to hybridize with a zone-centre magnon mode, under the application of an external field [19][20][21] .…”

mentioning

confidence: 97%

“…1(a)). One of the allowed lattice vibrations in this space group 19 , which is relevant for this paper is shown in Figure 1 For our experiment we employ the pump-probe technique to measure the photo-induced rotation of the probe polarisation. The literature abundantly demonstrates that this experimental scheme is able to track the lattice dynamics 17 , as well as the complete coherent and incoherent longitudinal and transverse dynamics of the Néel vector (which is the antiferromagnetic order parameter) [32][33][34][35][36][37] , provided that the symmetry of the investigated material allows quadratic magneto-optical effects, as it is the experimentally proven for FePS tuned independently of each other, are employed as pump and probe beams, as described elsewhere 39 .…”

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confidence: 99%

“…Considering that our experiment was carried on a flake of FePS 3 deposited on a substrate, our results can be scaled down to a coherent THz modulation of the magnetocrystalline anisotropy in thinner flakes, even in the 2D limit, as FePS 3 and MnPS 3 , differently from NiPS 3 , retains the antiferromagnetic order 24 . In view of the phonon hybridisation with zone centre magnons [19][20][21] , applying an external magnetic field to this material can result in photoinducing even coherent phonomagnonic THz dynamics in a 2D antiferromagnet.…”

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confidence: 99%

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Ultrafast coherent THz lattice dynamics coupled to spins in a van der Waals antiferromagnetic flake

Mertens¹,

Mönkebüscher²,

Coronado³

et al. 2021

Preprint

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A coherent THz optical lattice mode is triggered by femtosecond laser pulses in the antiferromagnetic van der Waals semiconductor FePS 3 . The 380 nm thick exfoliated flake was placed on a substrate and laser-driven lattice and spin dynamics were investigated as a function of the excitation photon energy and sample temperature.The pump-probe spectroscopic measurements reveal that the photo-induced phonon is generated by a displacive mechanism. The amplitude of the phononic signal decreases as the sample is heated up to the Néel temperature and vanishes as the phase transition to the paramagnetic phase occurs. This evidence confirms that the excited lattice mode is intimately connected to the long-range magnetic order. Therefore our work discloses a pathway towards a femtosecond coherent manipulation of the magneto-crystalline anisotropy in a van der Waals antiferromagnet. In fact, it is reported that by applying a magnetic field the induced phonon mode hybridizes via the Kittel-mechanism with zone-centre magnons.

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Ultrafast Coherent THz Lattice Dynamics Coupled to Spins in the van der Waals Antiferromagnet FePS₃

et al. 2022

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Coherent THz optical lattice and hybridized phonon–magnon modes are triggered by femtosecond laser pulses in the antiferromagnetic van der Waals semiconductor FePS3. The laser‐driven lattice and spin dynamics are investigated in a bulk crystal as well as in a 380 nm‐thick exfoliated flake as a function of the excitation photon energy, sample temperature and applied magnetic field. The pump‐probe magneto‐optical measurements reveal that the amplitude of a coherent phonon mode oscillating at 3.2 THz decreases as the sample is heated up to the Néel temperature. This signal eventually vanishes as the phase transition to the paramagnetic phase occurs, thus revealing its connection to the long‐range magnetic order. In the presence of an external magnetic field, the optically triggered 3.2 THz phonon hybridizes with a magnon mode, which is utilized to excite the hybridized phonon–magnon mode optically. These findings open a pathway toward the optical control of coherent THz photo–magnonic dynamics in a van der Waals antiferromagnet, which can be scaled down to the 2D limit.

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Coherent strong-coupling of terahertz magnons and phonons in a Van der Waals antiferromagnetic insulator

Cited by 8 publications

References 37 publications

High pressure tuning of magnon-polarons in the layered antiferromagnet FePS$_3$

High pressure tuning of magnon-polarons in the layered antiferromagnet FePS$_3$

Ultrafast coherent THz lattice dynamics coupled to spins in a van der Waals antiferromagnetic flake

Ultrafast Coherent THz Lattice Dynamics Coupled to Spins in the van der Waals Antiferromagnet FePS₃

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Coherent strong-coupling of terahertz magnons and phonons in a Van der Waals antiferromagnetic insulator

Cited by 8 publications

References 37 publications

High pressure tuning of magnon-polarons in the layered antiferromagnet FePS$_3$

High pressure tuning of magnon-polarons in the layered antiferromagnet FePS$_3$

Ultrafast coherent THz lattice dynamics coupled to spins in a van der Waals antiferromagnetic flake

Ultrafast Coherent THz Lattice Dynamics Coupled to Spins in the van der Waals Antiferromagnet FePS3

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Ultrafast Coherent THz Lattice Dynamics Coupled to Spins in the van der Waals Antiferromagnet FePS₃