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Spatial Separation of Carrier Spin by the Valley Hall Effect in Monolayer WSe <sub/>2</sub> Transistors
摘要： We investigate the valley Hall effect (VHE) in monolayer WSe2 field-effect transistors using optical Kerr rotation measurements at 20 K. While studies of the VHE have so far focused on n-doped MoS2, we observe the VHE in WSe2 in both the n- and p-doping regimes. Hole doping enables access to the large spin-splitting of the valence band of this material. The Kerr rotation measurements probe the spatial distribution of the valley carrier imbalance induced by the VHE. Under current flow, we observe distinct spin-valley polarization along the edges of the transistor channel. From analysis of the magnitude of the Kerr rotation, we infer a spin-valley density of 44 spins/μm, integrated over the edge region in the p-doped regime. Assuming a spin diffusion length less than 0.1 μm, this corresponds to a spin-valley polarization of the holes exceeding 1%.
关键词： magneto-optical Kerr effect,Tungsten diselenide,valleytronics,spintronics
更新于2025-09-23 15:23:52
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Depinning Field of Vortex Domain Wall in Wide Magnetic Wires with Asymmetric Notches Using Magneto-Optical Kerr Effect Microscopy
摘要： We examined the pinning and depinning fields of the vortex domain wall (VDW) in wide permalloy wires to better understand VDW dynamic behavior. Our sample device has differently designed notches at the center of a 2-μm-wide wire. The notch depth ratio ranged from 0.2 to 0.8, and the asymmetric angles of the notches are 45°, 60°, and 75°. The depinning field was found to have two distribution ranges, similar to how the depinning field depends on VDW chirality in submicron size width wire. Our results also showed that the VDW depinning behavior of a wide wire is the same as that of a narrow wire. The asymmetric notch angle affected the depinning field, which was similar to the results of simulation with 400-nm wire. This suggests that the wide wire depinning field is similar to that of narrow wire.
关键词： vortex domain wall,Magneto-optical Kerr effect microscopy,depinning field
更新于2025-09-23 15:22:29
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Magnetic field sensor based on magnetoplasmonic crystal
摘要： Here we report on designing a magnetic field sensor based on magnetoplasmonic crystal made of noble and ferromagnetic metals deposited on one-dimensional subwavelength grating. The experimental data demonstrate resonant transverse magneto-optical Kerr effect (TMOKE) at a narrow spectral region of 50 nm corresponding to the surface plasmon-polaritons excitation and maximum modulation of the reflected light intensity of 4.5% in a modulating magnetic field with the magnitude of 16 Oe. Dependences of TMOKE on external alternating current (AC) and direct current (DC) magnetic field demonstrate that it is a possibility to use the magnetoplasmonic crystal as a high-sensitive sensing probe. The achieved sensitivity to DC magnetic field is up to 10?6 Oe at local area of 1 mm2.
关键词： sensitivity,surface plasmon-polaritons,transverse magneto-optical Kerr effect,magnetic field sensor,magnetoplasmonic crystal
更新于2025-09-23 15:21:01
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Comparing the anomalous Hall effect and the magneto-optical Kerr effect through antiferromagnetic phase transitions in Mn <sub/>3</sub> Sn
摘要： In the non-collinear antiferromagnet Mn3Sn, we compare simultaneous measurements of the anomalous Hall effect (AHE) and the magneto-optical Kerr effect (MOKE) through two magnetic phase transitions: the high-temperature paramagnetic/antiferromagnetic (AF) phase transition at the N(cid:2)eel temperature (TN (cid:2) 420 K) and a lower-temperature incommensurate magnetic ordering at T1 (cid:2) 270 K. While both the AHE and MOKE are sensitive to the same underlying symmetries of the AF non-collinear spin order, we ?nd that the transition temperatures measured by these two techniques unexpectedly differ by approximately 10 K. Moreover, the applied magnetic ?eld at which the AF order reverses is signi?cantly larger when measured by MOKE than when measured by AHE. These results point to a difference between the bulk and surface magnetic properties of Mn3Sn.
关键词： antiferromagnetic phase transitions,anomalous Hall effect,magneto-optical Kerr effect,Mn3Sn
更新于2025-09-19 17:15:36
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Tunable multimodal magnetoplasmonic metasurfaces
摘要： The spectrally controllable enhancement of the transverse magneto-optical Kerr effect is realized in 2D hybrid metal-dielectric magnetoplasmonic metasurfaces. The light diffracted at different interfaces allows one to manipulate light phase in the condition of plasmonic and waveguiding resonance excitation controllable via the azimuthal angle. The multimodal nature of the system provides the flexible tunability of its magneto-optical response.
关键词： azimuthal angle,magneto-optical Kerr effect,magnetoplasmonic metasurfaces,plasmonic resonance,waveguiding resonance
更新于2025-09-16 10:30:52
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Wide-band enhancement of the transverse magneto-optical Kerr effect in magnetite-based plasmonic crystals
摘要： The transverse magneto-optical Kerr effect (TMOKE) in magnetite-based magnetoplasmonic crystals is studied experimentally and theoretically. We analyze angle-resolved TMOKE spectra from two types of structures where noble metallic stripes are incorporated inside a thin magnetite film or located on top of a homogeneous film. A multiple-wide-band enhancement of the TMOKE signal in transmission is demonstrated. The complex dielectric permittivity and gyration are experimentally determined using the ellipsometry technique as well as Faraday rotation and ellipticity measurements. The obtained parameters are used in rigorous coupled-wave analysis (RCWA) calculations for studying the optical resonances. Our RCWA calculations of transmittance and TMOKE are in good agreement with the experimental data. The role of guiding and plasmonic modes in the TMOKE enhancement is revealed. We demonstrate that the TMOKE provides rich information about the studied optical resonances.
关键词： transverse magneto-optical Kerr effect,ellipticity measurements,gyration,magnetoplasmonic crystals,Faraday rotation,dielectric permittivity,optical resonances,RCWA,magnetite,TMOKE
更新于2025-09-12 10:27:22
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Efficiency evaluation of the transverse magneto-optical Kerr effect in magnetoplasmonic structures
摘要： In this study the new approach to the efficiency evaluation of the transverse magneto-optical Kerr effect is considered. To assess the prospects for the practical use of structures based on TMOKE, the Figure of Merit (FOM) parameter is introduced, which is the product of the reflected/transmitted light intensity and the Kerr signal of the structure. Kerr signal defined as absolute value of the difference of light intensities at opposite magnetizations. It is shown that parameter Figure of Merit (FOM) in proposed form can give more information than the most commonly used relative value of TMOKE. The advantages of the introduced parameter are demonstrated on the example of a magnetoplasmonic structure with thin magnetite films.
关键词： transverse magneto-optical Kerr effect,magnetoplasmonic structures,Figure of Merit,TMOKE
更新于2025-09-12 10:27:22
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Optical and Magneto-Optical Properties of Multilayer Nanosized [Co/TiO2]n Films
摘要： The optical and magneto-optical properties of the metal–dielectric multilayer [Co/TiO2]n structures with 2–4-nm-thick layers prepared on a silicon substrate Si(001) by ion-beam deposition have been studied. The complex permittivity of multilayer [Co/TiO2]n structures has been measured by the optical ellipsometry technique in the spectral range of 0.6–5.6 eV and analyzed using the optical reflection matrices for isotropic multilayer dielectric structures taking into account the optical losses and also using the method of anisotropic effective medium. The magneto-optical Kerr effect has been measured by the polarimetric technique in the spectral range of 1.2–4.5 eV in the polar and longitudinal geometries. The magnetic anisotropy type is determined on the base of the field dependences of the magneto-optical Kerr effect. It is found that the nanosized [Co/TiO2]n structures can be considered as artificial optically uniaxial media with a strong magnetic and optical anisotropy at room temperature.
关键词： silicon substrate,Co/TiO2,magneto-optical properties,multilayer nanosized films,optical properties,complex permittivity,magneto-optical Kerr effect,magnetic anisotropy,optical ellipsometry,ion-beam deposition
更新于2025-09-10 09:29:36