Fig. 3: NLMO effects in representative 2D magnets.
From: Giant and controllable nonlinear magneto-optical effects in two-dimensional magnets
a The NLMO angle and c NLMO intensity asymmetry as a function of frequency. The vertical dashed lines in the curves indicate the NLMO rotation is ill-defined at the corresponding frequencies, and the polarization-resolved SHG close to those frequencies in ABA-CrI3 and ML Cr2I3Br3 are shown in Supplementary Figs. 5a and 7a. b Change of polarization-resolved SHG under \({{{\mathcal{T}}}}\) operation at a LPL characteristic frequency \({\omega }_{{{{\rm{LPL}}}}}^{{\prime} }=1.71\) eV of ML Cr2I3Br3. The yellow line marks one of the LPL incident angles where the maximal polarization direction change of SHG happens under \({{{\mathcal{T}}}}\) operation. d CPL SHG intensity of FM and tFM states of ML Cr2I3Br3. The upper and lower panels are for incident helicity σ+ and σ−. The difference between the red and blue curves in each panel reflects the NLMO intensity asymmetry. For a particular magnetic order, the difference between the upper and lower panels reflects the magnitude of SHG-CD. The dashed yellow line indicates one of the CPL characteristic frequencies ωCPL = 1.57 eV of ML Cr2I3Br3. e Multi-degree controlling of NLMO in ML Cr2I3Br3. For linearly-polarized incident light at polarization angle θ = π/12 + nπ/6 and frequency \({\omega }_{{{{\rm{LPL}}}}}^{{\prime} }\), ML Cr2I3Br3 can act as a magneto-optical polarization switcher. For circularly polarized incident light at frequency ωCPL, ML Cr2I3Br3 can act as a magneto-optical switch for circularly polarized SH light or an optical filter for circularly polarized SH light with a particular helicity.
