Coupling of ferroelastic strain and ferroelectric phase transition in NiMnGa/Pb0.97La0.02(Zr0.95Ti0.05)O3 bilayered films

Coupling effects among mechanical, electrical and magnetic parameters in a material provide exciting opportunity for creating novel device functionalities. Here, bilayer composite films combining magnetic shape memory alloy Ni-Mn-Ga (NMG) and antiferroelectric (AFE) Pb0.97La0.02Zr0.95Ti0.05O3 (PLZT) have been fabricated. X-ray diffraction, magnetization, and magnetic domain measurements demonstrated an austenite-martensite transformation of NMG top-layer during the annealing. Meanwhile, an AFE to ferroelectric transition of the PLZT sub-layer is observed, which can be attributed to the interfacial stress coupling. The quantitative residual stress analysis revealed that the change of residual stress in the PLZT layer is up to 300 MPa during the annealing, confirming the ferroelastic stress transfer between the NMG and PLZT layers. These results open up a new pathway for interfacial elastic coupling driven multi-functionalities in composite films.