Abstract

Polarized and unpolarized neutron diffraction has been used to search for magnetic order in YBa2⁢Cu3⁢O6+x superconductors. Most of the measurements were made on a high-quality crystal of YBa2⁢Cu3⁢O6.6. It is shown that this crystal has highly ordered ortho-II chain order, and a sharp superconducting transition. Inelastic scattering measurements display a very clean spin-gap and pseudo gap with any intensity at 10 meV being 50 times smaller than the resonance intensity. The crystal shows a complicated magnetic order that appears to have three components. A magnetic phase is found at high temperatures that seems to stem from an impurity with a moment that is in the a −b plane but disordered on the crystal lattice. A second ordering occurs near the pseudo gap temperature that has a shorter correlation length than the high temperature phase and a moment direction that is at least partly along the c axis of the crystal. Its moment direction, temperature dependence, and Bragg intensities suggest that it may stem from orbital ordering of the d-density wave type. An additional intensity increase occurs below the superconducting transition. The magnetic intensity in these phases does not change noticeably in a 7 T magnetic field aligned approximately along the c axis. Searches for magnetic order in YBa2⁢Cu3⁢O7 show no signal while a small magnetic intensity is found in YBa2⁢Cu3⁢O6.45 that is consistent with the c axis directed magnetic order. The results are contrasted with other recent neutron measurements.

Department(s)

Materials Science and Engineering

International Standard Serial Number (ISSN)

2469-9969, 2469-9950

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2026 American Physical Society, All rights reserved

Publication Date

2002-10-30

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