Fig. 5. Calculated electron and hole g-factors in MAPbI₃.

a and c The calculated electron and hole g-factors in tetragonal MAPbI₃ as a function of the tetragonal crystal field (CF), $\delta$, with orthorhombic CF $\zeta =0$. b and d The electron and hole g-factors in orthorhombic MAPbI₃ for fixed tetragonal CF $\delta$=+349.8 meV, determined by fit to the measured g-factors, as a function of the orthorhombic CF, $\zeta$. The best-fit value for $\zeta$ is +147.7 meV, marked in panels (b, d) with a vertical dashed black line. The subscripts x, y and z on the g-factor components denote the [1,0,0], [0,1,0] and [0,0,1] crystallographic directions. In the calculations shown, the bandgap $E_g$, the SOC split-off parameter $\mathrm{\Delta }$, the Kane energy $E_p$, and Luttinger’s magnetic parameter $\kappa$ have the values shown in Table 1. From the values plotted, the g-factors along the $\left[1\overline{1}0\right]$ direction are obtained as²⁹ $g_{\left[1\overline{1}0\right]}^e=\sqrt{1/2{\left(g_{\mathrm{x}}^e\right)}^2+1/2{\left(g_{\mathrm{y}}^e\right)}^2}$; $g_{\left[1\overline{1}0\right]}^h=-\sqrt{1/2{\left(g_x^h\right)}^2+1/2{\left(g_y^h\right)}^2}$.