Incommensurate Spin Fluctuations in High-Transition Temperature Superconductors

• Published in: Science (American Association for the Advancement of Science) Vol. 277; no. 5329; pp. 1067 - 1071
• Main Authors: Wells, B. O., Lee, Y. S., Kastner, M. A., Christianson, R. J., Birgeneau, R. J., Yamada, K., Endoh, Y., Shirane, G.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for the Advancement of Science 22.08.1997; American Association for the Advancement of Science; The American Association for the Advancement of Science
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Crystals; Doping; Exact sciences and technology; Fluctuations (noise, chaos, nonequilibrium superconductivity, localization, etc.); Magnetic properties; Materials; Neutron scattering; Octahedrons; Oxygen; Physics; Properties of type I and type II superconductors; Research Article; Single crystals; Spin temperature; Superconductivity; Superconductors; Thermal properties; Temperature dependence; Phase diagrams; Lanthanum oxides; Phase transformations; Transition element compounds; Doping; Spin fluctuations; Rare earth compounds; Experimental study; Nonstoichiometry; Magnetic susceptibility; Strontium oxides; Inelastic scattering; Neutron scattering; High-Tc superconductors; Holes; Chemical composition; Quaternary compounds; Copper oxides; Carrier density
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.277.5329.1067

Neutron scattering experiments have revealed a fascinating interplay between the hole doping, the spin fluctuations, and the superconductivity of the cuprate superconductors. Recently, electrochemical techniques have been used to produce large single crystals of La$_2$CuO$_{4+y}$, which has mobile oxygen dopants. Staging behavior of the excess oxygen has been demonstrated, and the low-energy spin fluctuations in stage 6 La$_2$CuO$_{4+y}$ have been measured. The spin fluctuations are incommensurate with the lattice and have spatial, energy, and temperature dependencies very much like those in La$_{2-x}$Sr$_x$CuO$_4$, with similar high transition temperature. This establishes the universality of the incommensurate spin fluctuations among the La$_2$CuO$_4$-based superconductors.