Spin Order accompanying Loop-Current Order in Cuprates

TL;DR

This paper extends the theory of orbital current loop order in cuprates to include spin-orbit effects, predicting an accompanying in-plane spin order that aligns with experimental neutron scattering data.

Contribution

It introduces a microscopic theory showing that spin order must accompany loop-current order in cuprates, providing estimates for the spin moments and their directions.

Findings

In-plane spin order accompanies loop-current order.

Estimated magnitude of the ordered spin moments.

Consistency with neutron scattering polarization data.

Abstract

The theory of the long range order of orbital current loops in the pseudogap phase is generalized to include the effects of spin-orbit scattering. It is shown by symmetry arguments as well as by microscopic calculation that a specific in-plane spin-order must necessarily accompany the loop-current order. The microscopic theory also allows an estimate of the magnitude of the ordered spin-moment. Exchange coupling between the generated spins further modifies the in-plane direction of the spin moments. The structure and form factor for the spin and orbital moments combined with the induced spin order is consistent with the direction of moments deduced from polarization analysis in the neutron scattering experiment.