Instability in case C2 (top) and R2 (bottom). Shown are the temporal evolution of the poloidal magnetic energy in the first 11 azimuthal wavenumbers (averaged in r and θ) (left), the fluctuations of the radial component of the magnetic field at a particular longitude (mid) and the rotation profile (right) when the instability starts to develop, that is at t = 0.15t_ap for C2 and t = 0.35t_ap for R2. The color bar applies to the rotation rate.