Abstract
Multiferroic hexagonal manganites ReMnO3studied by optics are reviewed. Their electronic structures were revealed by static linear and nonlinear spectra. Two transitions located at~1.7 eV and~2.3 eV have been observed and attributed to the interband transitions from the lower-lying Mn3+dxy/dx2-y2anddxz/dyzstates to the Mn3+d3z2-r2state, respectively. These so-called d-d transitions exhibit a blueshift as decreasing temperatures and an extra blueshift nearTN. This dramatic change indicates that the magnetic ordering seriously influences the electronic structure. On the other hand, the ultrafast optical pump-probe spectroscopy has provided the important information on spin-charge coupling and spin-lattice coupling. Because of the strongly correlation between electronic structure and magnetic ordering, the amplitude of the initial rising component inΔR/Rshows striking changes at the vicinity ofTN. Moreover, the coherent optical and acoustic phonons were observed on optical pump-probe spectroscopy. Both the amplitude and dephasing time of coherent phonons also exhibit significant changes atTN, which provide the evidence for spin-lattice interaction in these intriguing materials.
Highlights
Multiferroic materials [1,2,3,4] with the coexistence of various ferroic order have attracted great attention in condensed matter research due to their great potential for applications in the fields of oxide electronics, spintronics, and even the green energy devices for reducing the power consumption
The ultrafast spectroscopies demonstrate the interaction between electron, phonon, and spin systems on multiferroic hexagonal manganites
The electronic structure of hexagonal manganites has been clearly depicted by linear and nonlinear optical spectroscopy, which further provides the basis for the excitation and relaxation of electrons in pump-probe spectroscopy
Summary
Multiferroic materials [1,2,3,4] with the coexistence of various ferroic order (ferromagnetic, ferroelectric, or ferroelastic) have attracted great attention in condensed matter research due to their great potential for applications in the fields of oxide electronics, spintronics, and even the green energy devices for reducing the power consumption. The properties of electricity and magnetism were combined into one common discipline by the Maxwell equations, the electric and magnetic orderings in solid-state materials are always considered separately. This is because that the electric charges of electrons and ions are responsible for the charge effects, whereas the electron spins govern the magnetic properties. The hexagonal manganite ReMnO3 compounds show a lattice distortion to enlarge their unit cell, which is the so-called geometric ferroelectricity [13,14,15]. The ultrafast spectroscopies demonstrate the interaction between electron, phonon, and spin systems on multiferroic hexagonal manganites.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
