Speaker: Daniel Khomskii - Physikalisches Institut, Universitaet zu Koeln, Germany
Date & Time: Thursday, July 13, 2017 @ 2:00pm
Location: AMPEL 311
Local Contact: George Sawatzky
In this talk, Professor Khomski will discuss some effects occurring in transition metal compounds with small or negative charge transfer gap and with large contribution of ligand (e.g. oxygen) holes. Special attention will be paid to the compounds of 4d and 5d elements. The apparent inversion of crystal field levels, as well as the tendency to spontaneous charge disproportionation will be discussed. Specifically, some systems containing gold, such as Cs2Au2Cl6 and AuTe2, will be discussed, and the question formulated in the title will be addressed. I will also mention some recent results concerning materials “in between” oxides and peroxides, and discuss stability of different crystal forms and oxidation states in those.