NOVEL MAGNETISM IN A MODEL CUPRATE SUPERCONDUCTOR
|Date/Time:||Thursday, 01 Sep 2011 - Saturday, 03 Sep 2011|
|Location:||Room 5 PHYSICS|
|Channel:||Condensed Matter Physics|
Magnetic correlations might cause the superconductivity in the cuprates and are generally believed to be antiferromagnetic. Following our success in growing sizable crystals of the structurally simple compound HgBa_2CuO_(4+delta) , we used polarized neutron diffraction to demonstrate the universal existence of a novel type of magnetic order in superconducting samples . Unlike antiferromagnetism, this order does not break the lattice translational symmetry. Our inelastic neutron scattering measurements confirmed the existence of the well-known magnetic resonance at the antiferromagnetic point  and to led to the insight that the resonance energy is universally related to the superconducting gap in several families of unconventional superconductors . These experiments also resulted in the discovery of several excitations branches that appear to be fundamental collective modes associated with the novel magnetic order . This pseudogap magnetism is consistent with a particular type of order involving circulating charge currents and with the notion that the phase diagram of the cuprates is controlled by an underlying quantum critical point .
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