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Central mode and spin confinement near the boundary of the superconducting phase in YBa2Cu3O6.353 (Tc=18 K)

C. Stock·W. J. L. Buyers·Z. Yamani·C. Broholm·J. -H. Chung·Z. Tun·R. Liang·D. Peets·D. Bonn·W. N. Hardy·R. J. Birgeneau
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Abstract

We have mapped the neutron scattering spin spectrum at low-energies in YBa2Cu3O6.353 (Tc=18 K) where the doping ~0.06 is near the critical value (pc=0.055) for superconductivity. No coexistence with long range ordered antiferromagnetism is found. The spins fluctuate on two energy scales, one a damped spin response with a ~2 meV relaxation rate and the other a central mode with a relaxation rate that slows to less than 0.08 meV below Tc. The spectrum mirrors that of a soft mode driving a central mode. Extremely short correlation lengths, 42+-5 Angstrom in-plane and 8+-2 Angstrom along the c direction, and isotropic spin orientations for the central mode indicate that the correlations are subcritical with respect to any second order transition to Neel order. The dynamics follows a model where damped spin fluctuations are coupled to the slow fluctuations of regions with correlations shortened by the hole doping.

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C. Stock, W. J. L. Buyers, Z. Yamani, C. Broholm, J. -H. Chung, Z. Tun, R. Liang, D. Peets, D. Bonn, W. N. Hardy, R. J. Birgeneau. 2006-02-15. Central mode and spin confinement near the boundary of the superconducting phase in YBa2Cu3O6.353 (Tc=18 K). https://doi.org/10.1103/physrevb.73.100504

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