Intersite Charge Transfer and Ordering and Improper Ferroelectric Polarization in AMn7O12 Perovskite Oxides
Wei-Tin Chen1,2*, Chin-Wei Wang3, Hung-Cheng Wu4, Fang-Cheng Chou1,2,3, Hung-Duen Yang4, Arkadiy Simonov5, M. S. Senn6
1Center for Condensed Matter Sciences, National Taiwan University, Taipei, Taiwan
2Taiwan Consortium of Emergent Crystalline Materials, MOST, Taipei, Taiwan
3National Synchrotron Radiation Research Center, Hsinchu, Taiwan
4Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan
5Department of Chemistry, University of Oxford, Oxford, UK
6Department of Chemistry, University of Warwick, Coventry, UK
* Presenter:Wei-Tin Chen,
The design and discovery of novel functional materials for magnetic, electronic, spintronic and energy technology applications stimulate much of modern chemistry, physics and materials science. Multiferroics materials, for instance, attract considerable attentions in recent decades, having great potential to realize future generations of solid state storage devices. However, the essential issues such as the operational temperature and the strength of the coupling between the electric and magnetic polarizations need to be overcome before this technology can be realized in application. Recently, CaMn7O12 is reported to be the Type-II multiferroic and exhibiting the largest magnetoelectric response to date. In order to have further understanding of the coupling between the crystal structure and physical properties, a series of A-site ordered double perovskite AMn7O12 materials were prepared utilizing high-pressure high-temperature conditions. Structural analysis with synchrotron X-ray and neutron diffraction techniques were performed and rich spin, charge and orbital couplings were observed in these materials. A few recent discoveries of such exotic systems will be discussed in this presentation.

Keywords: High pressure synthesis, Improper ferroelectrics, Multiferroics, Perovskites