Fig. 2. Magnetic field-dependent Raman spectra of CrI₃.

Spectra are shown from 0 T to 3 T (B ⊥ ab plane) at T = 9 K where P₁ and P₂ disappear above B = 2.0 T, whereas ${\mathrm{A}}_{\mathrm{g}}^1$ and ${\mathrm{A}}_{\mathrm{g}}^6$ appear despite being forbidden in the xy polarization configuration. Yellow (green) shading highlights changes in P₁, P₂ (${\mathrm{A}}_{\mathrm{g}}^1$, ${\mathrm{A}}_{\mathrm{g}}^6$) as the magnetic field is varied. A vertical offset was applied to spectra at different field values. xx spectrum at B = 0 T shown at top for comparison.