2003 Fiscal Year Final Research Report Summary
Coexistence or competition of magnetism and electricity due to orbital ordering in transition-metal oxides
| Project/Area Number |
14540328
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
固体物性Ⅱ(磁性・金属・低温)
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
MIYASAKA Shigeki The University of Tokyo, School of Engineering, Research associate, 大学院・工学系研究科, 助手 (70345106)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TOKURA Yoshinori The University of Tokyo, School of Engineering, Professor, 大学院・工学系研究科, 教授 (30143382)
|
|---|
| Project Period (FY) |
2002 – 2003
|
| Keywords | orbital ordering / commensurate / incommensurate transition / manganese oxides / TbMnO_3 / ferroelectlicity / spin-orbital-lattice interaction / orthorhombic lattice distortion / magnetic-field-controlled ferroelectic polarization |
|---|
| Research Abstract |
In this term, we have investigated several systems, which have possibility of ferromagnetism and ferroelectlicity. Perovskite-type manganese oxide, TbMn_3 is one of such compounds. TbMnO_3 is an end material of hole-doped perobskite-type manganites, which show colossal magnetoresistance effect, and Mott Insulator. I this compound, orthorhombic lattice distortion is large, and the next-nearest-neighbor interaction between Mn spins is comparable to the nearest-neighbor one. These interactions cause the commensurate/incommensurate magnetic ordering at low temperatures. We succeeded in the crystal growth of a single-crystal of TbMnO_3 by using a floating zone method. We performed the X-ray analysis by using synchrotron S-ray and the single crystal of TbMnO_3. The present results indicate that this material undergoes the commensurate/incommensurate ordering of the orbital and lattice as well as the magnetic one. In the commensurate ordered phase, the ferroelectric polarization appears along b-axis. The magnetic field changes the direction of the ferroelectric polarization. We call the new phenomenon magnetic-field-controlled ferroelectic polarization. The magnetic field causes the flop of the Tb^3^+moment at low temperatures. The flop of Tb^3^+ moment induces that of Mn^3^+ spin via the interaction between Tb-Mn spins. Finally, the spin-orbital-lattice interplay in Mn ion causes the magnetic-field-controlled ferroelectic polarization.
|
