Creation of ferroelectric relaxor superlattices with symmetry braking and brain mimetic memory

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Superlattices of transition metal oxides have been formed by a laser Molecular Beam Epitaxy (MBE) technique connected with RHEED monitoring system. The superlattices of magnetics have been constructed on SrTiO_3(100), (110) and (111) surfaces. These surface selection enables us to control the three dimensional positioning of atoms and spin. In the case of LaCrO_3/LaFeO_3 superlattices on (111) surface, ferromagnetism has been realized for the first time. In the case of LaMnO_3/LaFeO_3 superlattices, on the other hand, spin frustration is expected competing with ferromagnetism of self-doped LaMnO_3 and anti-ferromagnetism of LaFeO_3 on SrTiO_3 (100) surface. Spin glass phase transition (casp shape in magnetization vs. temperature measurements) is observed in the case of LaMnO_3/LaFeO_3 superlattices. It is due to the spin frustration between ferromagnetic couping in LaMnO_3 layer and antiferromagnetic coupling in LaFeO_3 layer.