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New insights into the physics of the high-Tc cuprates from neutron, X-ray and transport measurements of HgBa2CuO4+d

Event Details

Event Dates: 

Thursday, November 7, 2013 - 12:00pm

Seminar Location: 

  • Duane Physics Room D142

Speaker Name(s): 

Martin Greven

Speaker Affiliation(s): 

University of Minnesota
Seminar Type/Subject

Scientific Seminar Type: 

  • Condensed Matter Seminar

Event Details & Abstract: 

Upon introducing charge carriers into the CuO2 sheets of the lamellar cuprates, the ground state evolves from a Mott insulator to a superconductor and, eventually, to a seemingly conventional Fermi-liquid metal. Much has remained elusive about the nature of this evolution, and about the peculiar metallic state at intermediate carrier concentrations where the superconducting transition temperature is maximized. Following our success in growing sizable crystals of the structurally simple model compound HgBa2CuO4+d (Hg1201) we have used polarized neutron diffraction to demonstrate the universal existence of a novel kind of magnetic order in superconducting samples. Unlike antiferromagnetism, this order that is associated with the so-called pseudogap phase does not break the lattice translational symmetry. Whereas our inelastic neutron scattering measurements confirm the existence of well-defined antiferromagnetic excitations, although with novel features, they also reveal several new excitations branches that appear to be fundamental collective modes associated with the novel magnetic order. These observations are consistent with the notion that the phase diagram is controlled by an underlying quantum critical point. I will furthermore discuss recent X-ray and resistivity experiments that reveal charge-density wave correlations and Fermi-liquid behavior deep in the pseudogap phase. (This work was supported by DOE-BES.)