Tunable layered-magnetism-assisted magneto-Raman effect in a two-dimensional magnet [CrI.sub.3]

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Date: Oct. 6, 2020
Publisher: National Academy of Sciences
Document Type: Report
Length: 4,854 words
Lexile Measure: 1720L

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Abstract :

We used a combination of polarized Raman spectroscopy experiment and model magnetism-phonon coupling calculations to study the rich magneto-Raman effect in the two-dimensional (2D) magnet [CrI.sub.3]. We reveal a layered-magnetism-assisted phonon scattering mechanism below the magnetic onset temperature, whose Raman excitation breaks time-reversal symmetry, has an antisymmetric Raman tensor, and follows the magnetic phase transitions across critical magnetic fields, on top of the presence of the conventional phonon scattering with symmetric Raman tensors in N-layer [CrI.sub.3]. We resolve in data and by calculations that the first-order [A.sub.g] phonon of the monolayer splits into an N-fold multiplet in N-layer [CrI.sub.3] due to the interlayer coupling (N[greater than or equal to]2) and that the phonons within the multiplet show distinct magnetic field dependence because of their different layered-magnetism-phonon coupling. We further find that such a layered-magnetism-phonon coupled Raman scattering mechanism extends beyond first-order to higher-order multiphonon scattering processes. Our results on the magneto-Raman effect of the first-order phonons in the multiplet and the higherorder multiphonons in N-layer [CrI.sub.3] demonstrate the rich and strong behavior of emergent magneto-optical effects in 2D magnets and underline the unique opportunities of spin-phonon physics in van der Waals layered magnets. two-dimensional layered magnetism | magneto-Raman effect | Raman spectroscopy

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Gale Document Number: GALE|A640357876