Fig. 2

Angle dependence of the magnetotropic coefficient. The magnetotropic coefficient k, proportional to the shift in frequency, of RuCl₃ at T = 16 K and B = 5 T (black points). The expected angle dependences of the magnetotropic coefficient (solid red line) and the magnetic torque (dashed red line) in the linear response regime M_i = χ_ijB_j are overlaying the data. θ = 0° and θ = 90° correspond to magnetic field applied perpendicular and parallel to the honeycomb planes, respectively. In the linear response regime, the principal magnetic axes (gray bands) have a maximal response in the magnetotropic coefficient, and these directions coincide with the zeros of the torque signal