2004 Fiscal Year Final Research Report Summary
Charge ordering and metal-insulator transition in mixed-valence transition metal oxcides
| Project/Area Number |
15540332
|
|---|
| 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 | Chiba University |
|---|
Principal Investigator |
OHAMA Tetsuo Chiba University, Graduate school of science and technology, associate professor, 大学院・自然科学研究科, 助教授 (80345008)
|
|---|
| Project Period (FY) |
2003 – 2004
|
| Keywords | NMR / electron correlation / magnetic structure / metal-insulator transition |
|---|
| Research Abstract |
Developement of NMR spectrometer
In this research, we need an NMR spectrometer with wide band width to observe the resonance in magnetically ordered states. We developed a spectrometer for 5 to 220MHz.
Charge ordering in vanadates
We studied the spin dynamics in the uniform state in a charge ordering system α'-NaV_2O_5. We observed low-dimensional behavior in the nuclear relaxation ; it agrees with our expectation from the crystal structure. The further understanding of this behavior and effects of charge fluctuation is a future problem.
Ferromagnetism in vanadates
In order to study the orbital and spin states and the magnetic excitations in insulating magnetic ordered states on frustrated lattices, we studied a vanadates with the pyrochlore structure Lu_2V_2O_7. We observed NMR spectra for Lu and V sites in the ferromagnetic state to investigate the orbital state. The experiments and the data analysis are in progress.
Antiferromagnetism in f-electron systems
In order to study magnetic ordering in metals and its relation with metal-insulator transition, we studied a metallic antiferromagnet UNiGa_5. We analyzed NMR spectra for the ligand Ga sites in the antiferromagnetic and paramagnetic phases and determined the quadrupole parameters and the internal fields at the Ga sites.
We proposed a new NMR analysis of magnetic structures with magnetic space group and the representation analysis of magnetic structure and applied it to UNiGa_5 (published in Phys.Rev.B).
|
Research Products
(8 results)
