Abstract
Using quasielastic neutron scattering (QENS), we have investigated a self-diffusive behavior of Li ions for both MnO and MnO spinels. In addition, we have carried out elastic and inelastic neutron scattering measurements using the same samples, to study the interrelationship between Li self-diffusion, magnetism, and charge distribution in the lattice. From the QENS results, the self-diffusion of Li was observable above 280 K, and a self-diffusion coefficient () for MnO was estimated as cm/s at 400 K. for MnO was comparable to that for MnO. Furthermore, combining with the results of elastic and inelastic measurements, it was found that MnO undergoes a transition from a low-temperature () short-range charge-ordered (SRCO) phase to a high- charge-disordered (CDO) phase at 280 K. The structure of the SRCO was determined as a hexagon, because the formation of hexagon spin clusters was deduced from a magnetic diffuse scattering at low . Assuming the presence of the SRCO-CDO transition at 280 K, both the anomaly of the diffusive behavior at 280 K and the local lattice distortion below 280 K are reasonably explained, despite the absence of long-range CO for MnO.
- Received 9 May 2010
DOI:https://doi.org/10.1103/PhysRevB.83.094401
©2011 American Physical Society