Ferroelectric Sm-doped BiMnO₃thin films with ferromagnetic transition temperature enhanced to 140 K

A combined chemical pressure and substrate biaxial pressure crystal engineering approach was demonstrated for producing highly epitaxial Sm-doped BiMnO₃(BSMO) films on SrTiO₃single crystal substrates, with enhanced magnetic transition temperatures, T_Cup to as high as 140 K, 40 K higher than that for standard BiMnO₃(BMO) films. Strong room temperature ferroelectricity with piezoresponse amplitude, d₃₃= 10 pm/V, and long-term retention of polarization were also observed. Furthermore, the BSMO films were much easier to grow than pure BMO films, with excellent phase purity over a wide growth window. The work represents a very effective way to independently control strain in-plane and out-of-plane, which is important not just for BMO but for controlling the properties of many other strongly correlated oxides.