In-plane magnetocrystalline anisotropy in the van der Waals antiferromagnet FePSe3_3 probed by magneto-Raman scattering

Magnon gap excitations selectively coupled to phonon modes have been studied in FePSe$_3$ layered antiferromagnet with magneto-Raman scattering experiments performed at different temperatures. The bare magnon excitation in this material has been found to be split (by $\approx~1.2$ cm$^{-1}$) into two components each being selectively coupled to one of the two degenerated, nearby phonon modes. Lifting the degeneracy of the fundamental magnon mode points out toward the biaxial character of the FePS$_3$ antiferromagnet, with an additional in-plane anisotropy complementing much stronger, out-of-plane anisotropy. Moreover, the tunability, with temperature, of the phonon- versus the magnon-like character of the observed coupled modes has been demonstrated.Comment: 7 pages, 5 figure

Role of structural dimensionality in the magneto-chiral dichroism of chiral molecular ferrimagnets

International audienceHere we report on magneto-chiral dichroism (MChD) detected with visible light on the chiral molecular ferrimagnet [{CrIII(CN)6}(MnIINH2ala)3]·3H2O (X = S, R; ala = alanine). Single crystals suitable for magneto-chiral optical measurements were grown starting from enantiopure precursors. X-ray diffraction and magnetic measurements confirmed the 3D-helical structure of the material, its absolute configuration, and its ferrimagnetic ordering below 35 K. Absorption and MChD spectra were measured between 520 and 900 nm from room temperature down to 4 K. At 4 K the electronic spectrum features spin-allowed and spin-forbidden transitions of CrIII centers and metal-to-metal charge transfer bands. The MChD spectra below the magnetic ordering temperature exhibit absolute configuration-dependent MChD signals, whose shape and intensity closely resamble that of a recently investigated 2D-layered chiral ferrimagnet featuring the same building blocks but different chiral ligands and a lower structural dimensionality. By comparing the temperature and magnetic field dependence of the MChD signals in these two chiral molecular ferrimagnets, we disentangle the role of structural dimensionality on MChD intensity and provide chemical design criteria towards highly responsive magneto-chiral optical materials

A Chiral Prussian Blue Analogue Pushes Magneto-Chiral Dichroism Limits

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Magnetic Anisotropy Drives Magnetochiral Dichroism in a Chiral Molecular Helix Probed with Visible Light

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Valley Zeeman Splitting and Valley Polarization of Neutral and Charged Excitons in Monolayer MoTe₂ at High Magnetic Fields

Semiconducting transition metal dichalcogenides (TMDCs) give rise to interesting new phenomena in external magnetic fields, such as valley Zeeman splitting and magnetic-field-induced valley polarization. These effects have been reported for monolayers (MLs) of the transition metal diselenides MoSe₂ and WSe₂ and, more recently, for disulfides MoS₂ and WS₂. Here, we present helicity-resolved magneto-photoluminescence and magneto-reflectance contrast measurements for MLs of the telluride member of the semiconducting TMDCs, 2H-MoTe₂, in magnetic fields up to 29 T in Faraday geometry. Well-resolved valley Zeeman splittings for the neutral A and B excitons (X_A⁰ and X_B⁰) and the charged exciton X^± are observed with effective g-factors of −4.6 ± 0.2, – 3.8 ± 0.6, and −4.5 ± 0.3, respectively. The magnetic field induced valley polarization of X_A⁰ and X^± reaches 78% and 36%, respectively, at a magnetic field of 29 T

Validation of microscopic magnetochiral dichroism theory

International audienceMagnetochiral dichroism (MChD), a fascinating manifestation of the light-matter interaction characteristic for chiral systems under magnetic fields, has become a well-established optical phenomenon reported for many different materials. However, its interpretation remains essentially phenomenological and qualitative, because the existing microscopic theory has not been quantitatively confirmed by confronting calculations based on this theory with experimental data. Here, we report the experimental low-temperature MChD spectra of two archetypal chiral paramagnetic crystals taken as model systems, tris(1,2-diaminoethane)nickel(II) and cobalt(II) nitrate, for light propagating parallel or perpendicular to the c axis of the crystals, and the calculation of the MChD spectra for the Ni(II) derivative by state-of-the-art quantum chemical calculations. By incorporating vibronic coupling, we find good agreement between experiment and theory, which opens the way for MChD to develop into a powerful chiral spectroscopic tool and provide fundamental insights for the chemical design of new magnetochiral materials for technological applications

Magneto-Optical Sensing of the Pressure Driven Magnetic Ground States in Bulk CrSBr

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Magnetic 3d–4f Chiral Clusters Showing Multimetal Site Magneto-Chiral Dichroism

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Helicene-Based Ligands Enable Strong Magneto-Chiral Dichroism in a Chiral Ytterbium Complex

International audienceHere we report the first experimental observation of magneto-chiral dichroism (MChD) detected through light absorption in an enantiopure lanthanide complex. The and enantiomers of [Yb(()-)()] (X = , ; = 3-(2-pyridyl)-4-aza[6]-helicene; = 1,1,1,5,5,5-hexafluoroacetylacetonate), where the chirality is held by the helicene-based ligand, were studied in the near-infrared spectral window. When irradiated with unpolarized light in a magnetic field, these chiral complexes exhibit a strong MChD signal ( ca. 0.12 T) associated with the F ← F electronic transition of Yb. The low temperature absorption and MChD spectra reveal a fine structure associated with crystal field splitting and vibronic coupling. The temperature dependence of the main dichroic signal detected up to 150 K allowed, for the first time, the disentanglement of the two main microscopic contributions to the dichroic signal predicted by the MChD theory. These findings pave the way toward probing MChD in chiral lanthanide-based single-molecule magnets

Magneto-Chiral Dichroism in a One-Dimensional Assembly of Helical Dysprosium(III) Single-Molecule Magnets

International audienceHere we report magneto-chiral dichroism (MChD) detected through visible and near-infrared light absorption of a chiral dysprosium(III) coordination polymer. The two enantiomers [DyIII(H6(py)2)(hfac)3]n [H6(py)2 = 2,15-bis(4-pyridyl)ethynylcarbo[6]helicen