Speaker
Description
The spin dynamics of Mn$_4$Nb$_2$O$_9$ were studied by using inelastic neutron scattering. A spin-dynamic model is proposed to explain the observed spin-wave excitation spectrum. The model indicates that the exchange interactions along the chain direction are weakly ferromagnetic while the exchange interactions between the neighbour chains are strongly antiferromagnetic. Such a antiferromagnetic configuration in the hexagonal plane cause spin frustration with a spin gap of about 1.4 meV at the zone centre. The Mn$^{2+}$ ions in this material demonstrate a very weak easy-axis single-ion anisotropy. Critical scattering in the vicinity of T$_{N}$ was studied. On the basis of the magnetic structure and spin-dynamic models, the weak magnetoelectric coupling effect in Mn$_4$Nb$_2$O$_9$ is ascribed to the weak magnetostriction due to the subtle difference between Mn$^{2+}$ ions on the Mn$_{I}$ and Mn$_{II}$ sites.
| Level of Expertise | Experienced Researcher |
|---|---|
| Which facility did you use for your research | Australian Centre for Neutron Scattering |
| Students Only - Are you interested in AINSE student funding | No |
| Condition of submission | Yes |
| Pronouns | He/Him |
| Presenter Gender | Man |
| Do you wish to take part in the Student Poster Slam | No |
