Fig. 2: Beam shift-induced transverse photoresistance with a Wheatstone bridge model.

a The static component of the 2D transverse resistance mapping of the Pt Hall cross can be viewed as a Wheatstone bridge with four resistors R1, R2, R3, and R4. The temperature rises in areas illuminated by the laser spot, which increases the resistance. The transverse voltage is positive when R1 or R4 increases, and negative value when R2 or R3 increases; b–e Transverse photoresistance mapping measured at different sample orientations. f An illustration of a simulated pure helicity-dependent photoresistance (HPR) effect, along with the charge current distribution shown as gray arrows. The spin accumulation is assumed to be proportional to the curl of the current along the transverse direction in a high-symmetrical material system with spin diffusion length much shorter than the laser spot. The transverse HPR effect is calculated by multiplying the distribution of spin accumulation with the Hall bar sensitivity function (i.e., the static transverse resistance mapping in a.) The Hall cross is split into four areas named I to IV. The current gradient is largest on the edge of the cross, where on the right edges of the cross (regions II and IV), HPR behaves similarly as in a, since the HPR acts in the same way as the laser heating. Vice versa, on the right edges (regions I and III) the HPR acts in the opposite way; g–j Photoresistance mapping calculated by shifting the static component of the transverse resistance in different directions, which are indicated by solid arrows. The unit for x and y axis are in μm for all the panels.