Reversible fcc ↔ bcc transformation in freestanding epitaxially grown Fe–Pd ferromagnetic shape memory films

Using temperature-dependent X-ray diffraction and magnetization measurements, a reversible face-centered cubic (fcc) to body-centered cubic (bcc) structural transformation was confirmed in freestanding epitaxially grown Fe70Pd30Fe70Pd30 films after lift-off from their MgO (1 0 0) substrates—a transformation generally considered irreversible in bulk samples. The latter is accompanied by a distinct change of the sample magnetization. In contrast, substrate constraints were found to suppress the thermoelastic fcc to bcc transformation in substrate-attached films.