Home » Neutron scattering study of magnetic excitations in two high-temperature superconductors. by Guichuan Yu
Neutron scattering study of magnetic excitations in two high-temperature superconductors. Guichuan Yu

Neutron scattering study of magnetic excitations in two high-temperature superconductors.

Guichuan Yu

Published
ISBN : 9780549850670
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122 pages
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The high-transition-temperature (Tc) superconductors are the most studied strongly-correlated electron systems, both because of their high transition temperatures and because they exhibit highly unusual normal-state phenomena arising from strongMoreThe high-transition-temperature (Tc) superconductors are the most studied strongly-correlated electron systems, both because of their high transition temperatures and because they exhibit highly unusual normal-state phenomena arising from strong electronic correlations. These electronic correlations make the study of these lamellar copper oxides one of the most formidable challenges in condensed matter physics. The high- Tc superconductors are electron- or hole-doped antiferromagnetic Mott-insulators, and significant antiferromagnetic spin fluctuations are present even in the superconducting doping regime. The most striking feature in the magnetic excitation spectrum is a sharp collective magnetic resonance mode that is significantly enhanced in the superconducting state.-In order to address questions pertaining to the universal nature of the magnetic resonance and to its connection with the superconductivity, we perform inelastic neutron scattering measurements of the magnetic excitations in two very distinct compounds: hole-doped HgBa2CuO4+delta, with focus on the properties of the resonance in the optimally- and under-doped regime, and electron-doped Nd2-xCexCuO4+delta , where we study the low-energy magnetic excitations near optimal doping and are able to resolve several energy scales, one of which possibly the magnetic resonance. The measurements of HgBa2CuO4+delta were enabled by our success in growing unprecedentedly large single crystals using an encapsulation growth technique. Finally, we compare our results for the resonance energies with those for a large number of other unconventional d-wave superconductors, and demonstrate a direct connection between the magnetic resonance energy and the superconducting pairing gap.