Nandini Trivedi (The Ohio State University)

Topology and Correlations driving new materials, phases and phenomena

Quantum materials today can be classified as a function of the strength of Coulomb interactions U and spin orbit coupling λ, in units of the bandwidth W. At large U lie the 3d transition metal oxides that show phenomena such as colossal magneto- resistance and high Tc superconductivity. In the opposite quadrant we encounter topological band insulators with large λ but in weakly correlated s- and p- band materials. I will discuss the next frontier of 4d and 5d oxide materials in the central region of such a phase diagram and show how novel phases and phenomena arise from the close interplay of all three scales — λ , U and W. I will critically review the combination of computational methods that are necessary to address the richness of the 4d and 5d materials. The role of advanced spectroscopies such as angle resolved photoemission, inelastic neutron scattering, THz spectroscopy, and resonant x-ray scattering using circularly polarized photons, to identify different response functions of complex oxides will also be discussed.