Detail:

Abstract：
Vanadium oxides are the archetypal Insulator-to-Metal transition (IMT) systems and their properties have been triggering a huge attention for decades both theoretically and experimentally. Besides the popular V2O3 and VO2 compounds, where the vanadium valency is three and four respectively, mixed valence systems have been also synthesized giving rise to the vanadium-oxide Magneli phase VnO2n-1 =V2O3 +(n-2)VO2 (3<n<9). Except for V7O13, all vanadium oxides in the Magneli phase undergo a IMT often accompanied by structural and antiferromagnetic transitions indicating a strong interplay among electronic, lattice and spin degree of freedom. Those interaction generate exotic excitations around the IMT like strongly renormalized electrons, lattice/spin polarons and charge fluctuations that can be studied through infrared and terahertz spectroscopy. In this talk, I will present an infrared view about the IMT in the vanadium-oxide Magneli phase as induced by temperature, pressure and electric field and studied by Synchrotron-based infrared-techniques. Finally, I will discuss future experiments based on pump-probe time resolved terahertz spectroscopy aimed to disantengle the different degrees of freedom partecipating to the IMT.

C.V.：

Prof. Stefano Lupi was graduated and got its PhD in Physics at the Department of Physics, Sapienza University of Rome, Italy in 1993. After a period of post-doc in France at the Lure Synchrotron facility, He got a permanent position in Rome before as researcher and after as Associate Professor. Stefano Lupi is responsible of the Infrared Beamline SISSI at Elettra Synchrotron and of the TERASPARC Terahertz beamline at SPARC-LAB INFN Frascati. He has published nearly 180 papers, including 3 Nature, 2 Nano Letters, and 14 Phys. Rev. Lett.