Abstract:

Resonant inelastic x-ray scattering (RIXS) is a technique for measuring the electronic excitation spectra.  As the field is maturing, increasingly lower energies are becoming accessible for measurement.  Recently, a 500 meV peak was observed in the zone-boundary RIXS spectrum of an undoped La2CuO4 crystal, measured at the copper K-edge.  This peak was suspected to be a 2-magnon excitation, but to make sure, we took several measurements – at different momenta, dopings, and temperatures.  In addition to verifying the peak assignment, interesting scaling behavior in the temperature dependence was observed, and the physics of the 2-magnon at finite momentum is discussed.