レーザMBE法による機能性酸化物人工格子の形成とスピン制御(<小特集>化学的方法による機能性酸化物膜の合成)
2000 年 27 巻 3 号 p. 117-123
詳細
2000 年 27 巻 3 号 p. 117-123
Superlattices of transition metal oxides have been constructed by a laser Molecular Beam Epitaxy (MBE) technique combinded with RHEED monitoring system. Not only ferroelectric superlattices but also magnetic superlattices have been constructed on SrTiO_3(100), (110) and (111) surfaces. These surface selections enables us to control the three dimensional positioning of atoms and spins. 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 antiferromagnetism 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 Iayer. This behavior is quite different from that of non-doped LaFeO_3/LaCrO_3 superlattices.
