a–c As-measured Raman spectra at T ≈ 5 K. For H//a, α-RuCl3 passes successively from a zigzag antiferromagnetic- through an intermediate- to a field-polarized-phase with increasing magnetic fields. The color shading denotes the broad continuum (C) on top of well-defined sharp peaks of magnetic origin (M1, 2M, 3M) and phonon modes (Eg(1) and Eg(2)). d–f Color contour plots of the Raman scattering intensity evolution with magnetic fields aligned along (100), (010), and (110), respectively. The dashed line in d denotes the gap of the fractionalized continuum as a function of field. g–i Respective sets of raw Raman data. j Field-dependence of the sharp low-energy magnetic excitations compared for different field directions.