Fig. 4. Flexure strain and anisotropy model.

a,b, Non-uniform strain distribution, ε_xx, in the α-Fe₂O₃ layer as a function of thickness and length, across folds in buffered AFM membranes (type C) with α-Fe₂O₃-side-facing-up (a) and buffer-side-facing-up (b) configurations. Membrane thickness has been exaggerated to aid the visualization of the non-uniform strain distribution as a function of thickness. The neutral line (ε_xx ≈ 0), indicated in yellow, is located at very different positions in a and b relative to the middle of the α-Fe₂O₃ layer, resulting in strong variations in the average and maximum strains in the AFM layer. c,d, Evolution of the thickness-averaged strain in the α-Fe₂O₃ layer, 〈ε_xx〉_z,F, and the corresponding local $T_{\mathrm{M}}/T_{\mathrm{M}}^{\mathrm{FF}}$ for the two configurations given in a (c) and b (d). Strain-driven modulation of the local T_M was obtained from the model developed in the literature³⁰. Here $T_{\mathrm{M}}/T_{\mathrm{M}}^{\mathrm{FF}}$ larger and smaller than unity refers to the elevation and suppression of the local Morin temperature, respectively, and therefore the magnetic anisotropy, relative to the flat far-field regions.