Electronic Structures of Multiferroics Studied Using Soft X-rays

Di-Jing Huang^1*

¹National Synchrotron Radiation Research Center, Hsinchu, Hsinchu, Taiwan

* Presenter:Di-Jing Huang, email:djhuang@nsrrc.org.tw

Magnetoelectric materials which possess more than one ferroic order have attracted much interest because of the spontaneous coexistence of electricity and magnetism. The magnetoelectric (ME) effect is a key in designing novel multiferroic devices. In this talk, we present soft X-ray spectroscopy studies on multiferroics, including polar magnet Fe2Mo3O8 and lacunar spinels.
The polar magnet Fe2Mo3O8 shows not only strong ME coupling but also chemical-doping controllability of the distinct ME phases. Our results of high-resolution soft resonant inelastic X-ray scattering (RIXS) measurements disentangle the electronic properties of octahedral and tetrahedral Fe2+ and provide spectroscopic evidence that the doped Zn favours to replace tetrahedral Fe in the doped compound. The lacunar spinels (AV4S8) with A=Ga and Ge, are unique in known skyrmions because of a sizable ferroelectric polarization of ~ 1 μC/cm2 and polar crystal structure. Recently, orbitally driven ferroelectricity and Néel-type insulating skyrmion phase were discovered in AV4S8. The origin of skyrmion phase has been attributed to exchange striction mechanism; however detailed microscopic mechanism is not clear yet. We used RIXS and photoemission spectroscopy to investigate the electronic properties of these compounds.

Keywords: quantum materials, cuprate superconductors, multiferroics, RIXS