| Project/Area Number |
15540331
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Condensed matter physics II
|
|---|
| Research Institution | TOHOKU UNIVERSITY (2004)
University of Tsukuba (2003) |
|---|
Principal Investigator |
ARIMA Takahisa TOHOKU UNIVERSITY, INSTITUTE OF MULTIDISCIPLINARY RESEARCH FOR ADVANCED MATERIALS, Professor, 多元物質科学研究所, 教授 (90232066)
|
|---|
| Project Period (FY) |
2003 – 2004
|
| Project Status |
Completed (Fiscal Year 2004)
|
| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2003: ¥2,900,000 (Direct Cost: ¥2,900,000)
|
|---|
| Keywords | manganite / crystal growth / colossal magnetoresistance / neutron scattering / synchrotron x-ray / Raman scattering / double perovskite |
|---|
| Research Abstract |
Single-crystal growth of double-perovskite NdBaMn2O6, which locates near the multicritical point among ferromagnetic metal, antiferromagnetic charge-ordered insulator, and antiferromagnetic two-dimensional metal, was tried. Transport measurements of twin single crystals show the significant reduction of Neel temperature of about 280 K by application of a magnetic field. Giant negative magnetoresistance along the c axis was observed ; resistivity at 240 K decreases by 1/30.
Competing among the abovementioned three phases in the A-site ordered RBaMn2O6 system was investigated by X-ray diffuse scattering. Raman scattering spectroscopy was also performed to observe the effect of charge/orbital ordering in this system, where charge/orbital ordered MnO2 sheets attack along the c axis in a different manner from the conventional A-site-disordered perovskite manganese oxides (R,A)MnO3.
Detail study of neutron diffraction in NdBaMn2O6 shows that ferromagnetically ordered MnO2 sheets antiferromagnetically stack along the c-axis. Lattice parameters a and b are suddenly elongated below Neel temperature, while the c length shrinks. This anomaly in lattice parameters clearly demonstrates that the ferro-type ordering of x2-y2 orbitals is formed simultaneously at the ordering of the Mn spin sector.
|
