1. The Myron Strongin Seminar

    "Time-Stamping the Magnetic Correlations in Photo-Doped Mott Insulator Sr2IrO4"

    Presented by Yue Cao, BNL

    Monday, November 2, 2015, 1:30 pm
    ISB Conf. Room 201, Bldg. 734

    This talk will explain how X-ray Free Electron Lasers (XFELs) provide a unique opportunity to directly determine the magnetic correlations in transient photo-excited states. We made the first implementation of time-resolved resonant inelastic X-ray scattering (tr-RIXS) at LCLS. We photo-dope a model quantum antiferromagnetic Mott insulator Sr2IrO4 and show how tr-RIXS directly clarifies the nature of ultrafast magnetic and orbital dynamics. We find that the non-equilibrium state 2 ps after photo-excitation has strongly suppressed long range magnetic order, but hosts photo-carriers that induce strong, non-thermal magnetic correlations. The magnetism restores its two-dimensional (2D) in-plane Neel correlations on a timescale of a few ps, while the three dimensional (3D) long-range magnetic order recovers over a far longer timescale of a few 100 ps. As an attractive, powerful new spectroscopy, and with construction plans at major XFEL facilities around the world, tr-RIXS will provide time, energy and momentum resolved insights into the magnetic, as well as orbital and charge excitations in correlated electron systems.