Physical origin of Davydov splitting and resonant Raman spectroscopy of Davydov components in multilayer<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi mathvariant="normal">MoTe</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>

Song, Qingjun; Tan, Qinghai; Zhang, Xin; Wu, Jiang-Bin; Sheng, Bowen; Wan, Yi; Wang, X. Q.; Dai, Li‐Xin; Tan, Ping‐Heng

doi:10.1103/physrevb.93.115409

Cited by 105 publications

(168 citation statements)

References 41 publications

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“…Such splitting is termed as Davydov splitting (41,42). Given the facts of the spectrum weight transfer behavior and small frequency difference between the split and original A 2 modes, we suggest that the split new peak at 127 cm -1 is originated from the Davydov splitting.…”

Section: Resultsmentioning

confidence: 79%

Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI₃

Zhang

Lyu

et al. 2019

Nano Lett.

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The recent discovery of 2D magnets has revealed various intriguing phenomena due to the coupling between spin and other degree of freedoms (such as helical photoluminescence, nonreciprocal SHG). Previous research on the spin-phonon coupling effect mainly focuses on the renormalization of phonon frequency. Here we demonstrate that the Raman polarization selection rules of optical phonons can be greatly modified by the magnetic ordering in 2D magnet CrI 3 . For monolayer samples, the dominant A 1g peak shows abnormally high intensity in the cross polarization channel at low temperature, which is forbidden by the selection rule based on the lattice symmetry. While for bilayer, this peak is absent in the cross polarization channel for the layered antiferromagnetic (AFM) state and reappears when it is tuned to the ferromagnetic (FM) state by an external magnetic field. Our findings shed light on exploring the emergent magneto-optical effects in 2D magnets.

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Section: Resultsmentioning

confidence: 79%

Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI₃

Zhang

Lyu

et al. 2019

Nano Lett.

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“…Davydov splitting is more pronounced at resonance, which is consistent with previous reports on WS 2 and MoTe 2 . [17,30] In the moderate/heavy electron doping region when there is no splitting, increases of V tg causes A 1g mode to blue-shifts when excitation wavelength is 612.2 nm while red-shifts when 632.9 nm is used.…”

Section: Resultsmentioning

confidence: 99%

“…[15] The dependence of Raman spectroscopy on the excitation energy may provide further information of the material properties, such as Davydov splitting and exciton-phonon coupling under resonant condition. [17][18][19][20] However, previous Raman spectroscopy studies in MoS 2 with electrostatic (2 of 6) 1701039 www.small-journal.com doping have not addressed the influence of excitation energy on the phonon behavior. Here, we present our results on gate-tunability of phonon properties using resonant Raman spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Gate‐Tunable Resonant Raman Spectroscopy of Bilayer MoS₂

Utama

Wang

et al. 2017

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The gate‐tunable phonon properties in bilayer MoS2 are shown to be dependent on excitation energy. Raman intensity, Raman shift, and linewidth are affected by resonant excitation, while a nonresonant laser does not influence the intensity significantly. The gate‐dependent Raman shift of A1g mode (either blue‐, red‐, or no‐shift) is a result of the combined effect of antibonding electron and resonant‐related decoupling effect. Although the decoupling effect cannot be directly measured due to the resonant background, it can be indirectly and qualitatively probed by observing A1g mode. This study on gate‐tunable resonant Raman spectroscopy has clarified the influence of carrier doping on phonon properties and demonstrates a new degree of freedom in manipulating phonons in 2D material systems.

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“…The appearance of the two Raman peaks in the AFM state and the dependence of the crosslinearly polarized spectra on the magnetic order can be understood by treating the CrI3 bilayer as a coupled spring system 21,22 . In a monolayer, the A1g peak at 127.4 cm -1 corresponds to a phonon mode describing an out-of-plane motion of the two iodine layers (Fig.…”

mentioning

confidence: 99%

Tuning inelastic light scattering via symmetry control in the two-dimensional magnet CrI3

et al. 2020

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The coupling between spin and charge degrees of freedom in a crystal imparts strong optical signatures on scattered electromagnetic waves. This has led to magneto-optical effects with a host of applications, from the sensitive detection of local magnetic order to optical modulation and data storage technologies. Here, we demonstrate a new magnetooptical effect, namely, the tuning of inelastically scattered light through symmetry control in atomically thin chromium triiodide (CrI3). In monolayers, we found an extraordinarily large magneto-optical Raman effect from an A1g phonon mode due to the emergence of ferromagnetic order. The linearly polarized, inelastically scattered light rotates by ~40⁰, more than two orders of magnitude larger than the rotation from MOKE under the same experimental conditions. In CrI3 bilayers, we show that the same A1g phonon mode becomes Davydov-split into two modes of opposite parity, exhibiting divergent selection rules that depend on inversion symmetry and the underlying magnetic order. By switching between the antiferromagnetic states and the fully spin-polarized states with applied magnetic and electric fields, we demonstrate the magnetoelectrical control over their selection rules. Our work underscores the unique opportunities provided by 2D magnets for controlling the combined time-reversal and inversion symmetries to manipulate Raman optical selection rules and for exploring emergent magneto-optical effects and spin-phonon coupled physics. Main text:Raman scattering measures light inelastically scattered from collective quasiparticle excitations. Since it is highly sensitive to material parameters such as crystal symmetry and local electronic states, Raman spectroscopy has provided a powerful probe of a broad range of condensed matter phenomena, such as charge density waves 1 , superconductivity 2 , ferroelectricity 3 , and topological physics 4 . In particular, Raman scattering from spin-phonon excitations has yielded incisive information on magnetic materials. For instance, in recently developed 2D van der Waals magnets, Raman scattering has been used to reveal magnetic order and phase transitions 5-7 down to a single layer [8][9][10] .Chromium triiodide (CrI3), a van der Waals magnet, was shown to be a layered antiferromagnet in its few-layer form: spins within each layer are ferromagnetically (FM) coupled with strong outof-plane anisotropy, while the interlayer exchange is antiferromagnetic (AFM) 11 . For bilayers, the system undergoes a spin-flip transition upon the application of a moderate magnetic field 11 , switching from a layered AFM state to a fully spin-polarized state. In addition, magneto-optical effects manifest strongly and in distinctly novel ways in CrI3. Examples include the very large magnetic-optical Kerr effect (MOKE) 11,12 and spontaneous helical light emission 13 from ferromagnetic monolayers, and electric-field induced Kerr rotation [14][15][16] and giant second-order nonreciprocal optical effects 17 in antiferromagnetic bilayers. Content:Extended Data...

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Physical origin of Davydov splitting and resonant Raman spectroscopy of Davydov components in multilayerMoTe2

Cited by 105 publications

References 41 publications

Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI₃

Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI₃

Gate‐Tunable Resonant Raman Spectroscopy of Bilayer MoS₂

Tuning inelastic light scattering via symmetry control in the two-dimensional magnet CrI3

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Physical origin of Davydov splitting and resonant Raman spectroscopy of Davydov components in multilayerMoTe2

Cited by 105 publications

References 41 publications

Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI3

Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI3

Gate‐Tunable Resonant Raman Spectroscopy of Bilayer MoS2

Tuning inelastic light scattering via symmetry control in the two-dimensional magnet CrI3

Contact Info

Product

Resources

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Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI₃

Magnetic Order-Induced Polarization Anomaly of Raman Scattering in 2D Magnet CrI₃

Gate‐Tunable Resonant Raman Spectroscopy of Bilayer MoS₂