Left: unpolarized ARPES spectrum from Sr 2 RuO 4 along the direction orthogonal to the crystal mirror plane, corresponding to the dashed line in Fig. 1c. Middle and right: the spectrum has been obtained by summing both contributions from right- (middle) and left-circularly (right) polarized light. Here we refer to this as C +, ( k , , ) to indicate signals from right- or left-circularly polarized light, collected at momentum k , and with a spin-up or spin-down channels, respectively.
