2010 Fiscal Year Final Research Report
A neutron scattering study on dynamical structure in β-pyrochlore oxide
| Project/Area Number |
21840020
|
|---|
| Research Category |
Grant-in-Aid for Research Activity Start-up
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
Condensed matter physics I
|
|---|
| Research Institution | The University of Tokyo |
|---|
Principal Investigator |
KOFU Maiko The University of Tokyo, 物性研究所, 助教 (70549568)
|
|---|
| Project Period (FY) |
2009 – 2010
|
| Keywords | βパイロクロア酸化物 / ラットリング / 同形転移 / 中性子散乱 |
|---|
| Research Abstract |
Inβ-pyrochlore oxide KOs_2O_6, a λ-shaped anomaly in heat capacity is observed below its superconducting transition temperature. This anomaly originates in a structure phase transition, but its origin is unknown. We ha ve carried out high -resolution neutron powder diffraction measurements on high quality and small crystals of KOs_2O_6 in order to investigate the crystal structure below and above the transition. It is found that the phase transition is an isomorphic one without symmetry breaking. Besides, in the low-temperature phase, the cage volume expands and the density distribution of K ions becomes broader, indicating that the ground state of rattling motion changes at the transition.
|
