single crystals using magneto-Raman spectroscopy*

We study in detail the structural and magnetic excitations of CrI₃ in single crystalline thin flakes using inelastic light scattering in a magnetic field. We find that for fields above 6 T we observe the scattering from the zone center magnon, the ferromagnetic resonance, with a linear dependence on the magnetic field in this range. This behavior is well explained by the classical Kittel formula that predicts a value of the zero-field resonance at approximately 45 GHz with an effective g-factor of ~ 2. We also find that as a function of the scattered polarization angle with respect to the incoming polarization, the intensity has a two-fold symmetric pattern without nodes (i.e. the signal does not vanish). We will discuss the possible reasons for this behavior and compare it to that expected for the lattice excitations for the expected magnetic point group symmetry.