Figure 69.

(a) Top: Experimental Raman spectra (left) and theoretical calculations (right) of magnon modes in bulk CrI₃ as a function of out-of-plane magnetic field (easy axis). Above B_c ∼ 2 T, a single mode is observed as expected for a fully spin-polarized state for all layers. Below B_c, two additional modes are seen that disperse oppositely with field, corresponding to the layer-AF order on surface layers. Bottom: Schematic of spins in bulk CrI₃ above and below B_c. Adapted with permission under a Creative Commons CC BY 4.0 license from ref (218). Copyright 2020 American Physical Society. (b) Field-dependent Raman spectra of bilayer CrI₃. Only layer-AF magnons modes are obtained. Adapted with permission from ref (794). Copyright 2020 Springer Nature.