The Frustration-induced Ferroelectricity of a Manganite Tricolor Superlattice with Artificially Broken Symmetry.

In this paper, [(LaSrMnO)/(PaCaMnO)/(LaSbMnO)] superlattices films have been deposited on (001) Nb:SrTiO substrates by a laser molecular-beam epitaxy technology. Expected ferroelectricity arise at well-defined tricolor superlattice at low temperature, composed of transition metal manganite, which is absent in the single-phase compounds. Furthermore, the ferroelectric properties of the superlattices are enhanced by increasing the periodicity m, which may be attributed to the accumulation of the polarization induced by the frustration. As for the magnetic hysteresis loop characteristics of the multilayer structures, the saturation magnetization and magnetic coercivity of films present definitely a strong periodic dependence. It also indicates that the frustration may exist in the tricolor superlattice. Our results further verify the previous theoretical research of generating multiferroics experimentally paving a way for designing or developing the novel magnetoelectric devices based on manganite ferromagnets.