Dispersive excitations in the high-temperature superconductor La2-xSrxCuO4
High-resolution neutron scattering experiments on optimally doped La2-xSrxCuO4 (x=0.16) reveal that the magnetic excitations are dispersive. The dispersion is the same as in YBa2Cu3O6.85, and is quantitatively related to that observed with charge sensitive probes. The associated velocity in La2-xSrxCuO4 is only weakly dependent on doping with a value close to the spin-wave velocity of the insulating (x=0) parent compound. In contrast with the insulator, the excitations broaden rapidly with increasing energy, forming a continuum at higher energy and bear a remarkable resemblance to multiparticle excitations observed in 1D S=1/2 antiferromagnets. The magnetic correlations are 2D, and so rule out the simplest scenarios where the copper oxide planes are subdivided into weakly interacting 1D magnets.
Riso Natl Lab, Mat Res Dept, DK-4000 Roskilde, Denmark. Univ Coll London, London Ctr Nanotechnol, London WC1E 6BT, England. Univ Coll London, Dept Phys & Astron, London WC1E 6BT, England. Rutherford Appleton Lab, ISIS Facil, Didcot OX11 0QX, Oxon, England. ETH, Neutron Scattering Lab, CH-5232 Villigen, Switzerland. Paul Scherrer Inst, CH-5232 Villigen, Switzerland. Univ Chicago, James Franck Inst, Chicago, IL 60637 USA. Univ Chicago, Dept Phys, Chicago, IL 60637 USA. Univ Oxford, Dept Phys, Oxford OX1 3PU, England. Univ Bristol, HH Wills Phys Lab, Bristol BS8 1TL, Avon, England. Univ Tokyo, Inst Solid State Phys, Tokyo 1138656, Japan. Univ Tokyo, Dept Adv Mat Sci, Kashiwa, Chiba 2778651, Japan. Christensen, NB, Riso Natl Lab, Mat Res Dept, DK-4000 Roskilde, Denmark.
Record created on 2007-01-24, modified on 2016-08-08