1. Condensed-Matter Physics & Materials Science Seminar

    "Magnetic Structure, Excitations and Hybridization in La(2-x)Ba(x)CuO(4)"

    Presented by Jerod Wagman, McMaster University, Canada

    Thursday, October 31, 2013, 1:30 pm
    Interdisciplinary Science Bldg. 734, Sem. Rm. 201

    Hosted by: Igor Zaliznyak

    The mechanism underlying high temperature superconductivity has been the subject of intense debate since the discovery of the first high temperature superconductor, La2-xBaxCuO4. Much of the research on these systems has focused on the correlation between magnetic structures and fluctuations with superconducting ground states. In the Cuprates, this correlation is manifest as the evolution of an insulating, three dimensional, commensurate antiferromagnet to a superconducting, two dimensional, incommensurate antiferromagnet with doping. I will discuss a series of recent single crystal neutron scattering studies on La2-xBaxCuO4. I will explain how our results motivate a phase diagram that is both purely magnetic and captures much of the complexity of standard high temperature superconductor phase diagrams. I will then discuss how our measurements demonstrate pronounced structure in the energy dependence of the magnetic scattering near (1/2,1/2,L) wavevectors. By considering the inelastic scattering both at low |Q| magnetic zone centers as well as the scattering at equivalent higher |Q| positions, I will show that this rich structure is a consequence of hybridization between highly dispersive spin excitations with weakly dispersive phonons.