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arXiv · 1501.02427

Ferro-type order of magneto-electric quadrupoles in the pseudo-gap phase of YBa2Cu3O6 + x unearthed by neutron diffraction

S. W. Lovesey·D. D. Khalyavin·U. Staub
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Abstract

A theory that fully describes previously observed neutron Bragg spots indicative of magnetic order in the pseudo-gap phase of YBa2Cu3O6 + x is presented. Magnetic diffraction intensities, unveiled by polarization analysis, are explained by parity-violating magnetic (magneto-electric) quadrupoles at in-plane Cu sites arranged in a simple ferro-type motif. An absence of conventional spin and orbital angular momentum dipoles in the theory is compatible with the occurrence of superconductivity and strongly suggests, moreover, that magneto-electric quadrupoles are the primary order-parameter in the pseudo-gap phase.

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S. W. Lovesey, D. D. Khalyavin, U. Staub. 2015-01-11. Ferro-type order of magneto-electric quadrupoles in the pseudo-gap phase of YBa2Cu3O6 + x unearthed by neutron diffraction. https://arxiv.org/abs/1501.02427

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