Speaker: Bum Joon Kim (Argonne National Laboratory) @ 3PM
Mott Physics in the Strong Spin-Orbit Coupling Limit: Using Resonant X-Ray Scattering to Probe Novel Magnetic States
Program Description
Competing interactions in transition metal oxides (TMO) lead to a wide array of charge, spin, and orbital ordered states, which are intimately related to many of the fascinating properties hosted by TMOs such as high-TC superconductivity and colossal magnetoresistance. The magnetism in TMOs has been studied extensively for many decades and is now well understood within the framework of Goodenough-Kanamori-Anderson. In the recent years, however, it has been realized that a novel class of oxide magnetism can emerge in MMOTTott insulators with strong relativistic spin-orbit coupling. In the strong spin-orbit coupling limit, relevant for 5d TMO iridates, localized electrons in a Mott insulator acquire exotic spin-orbit entangled structures, which enable novel expressions of magnetic interactions. An example of possible compelling outcome is the realization of the Kitaev model with a spin liquid ground state. In this talk, I will discuss how resonant elastic and inelastic x-ray scattering techniques can be used to study these novel magnetic orders and excitations.
Speaker: Narcizo Souza-Neto (Brazilian Synchrotron Light Laboratory) @ 4PM
X-Ray Spectroscopy at the New Brazilian Synchrotron Source: Applications in Magnetism and Extreme Conditions
Program Description
In view of the future synchrotron source in Brazil, currently in final design process, in this seminar will be given a brief overview of the first 13 beamlines planned with emphasis on x-ray spectroscopy covering energies from 1 keV to 30 keV. This will cover a broad range of scientific areas where X-ray absorption spectroscopy can be employed. As scientific motivation to the beamline capabilities, I will show examples of studies done at the Advanced Photon Source in the field of magnetism under high pressures. Specifically, I will show how complementary synchrotron x-ray spectroscopies (XANES/XMCD and NFS) together with XRD can thoroughly describe electronic and magnetic changes in rare earth materials under extreme pressures.
