Magnetic-field-induced chiral hidden order in URu2Si2

TL;DR

This paper proposes a unified explanation for the hidden order phenomena in URu2Si2 under magnetic fields, suggesting a chiral spin density wave as the underlying order parameter, and predicts observable Kerr angle signatures.

Contribution

It introduces a chiral dxy+idx2-y2 spin density wave model for the field-induced hidden order in URu2Si2, unifying previously puzzling experimental observations.

Findings

Explanation of double-step metamagnetic transitions

Prediction of non-linear Kerr angle dependence under magnetic fields

Unified phase diagram for hidden order phenomena

Abstract

Two of the most striking and yet unresolved manifestations of the hidden order (HO) in URu2Si2, are associated on one hand with the double-step metamagnetic transitions and on the other with the giant anomalous Nernst signal. Both are observed when a magnetic field is applied along the c-axis. Here we provide for the first time a unified understanding of these puzzling phenomena and the related field-temperature (B-T) phase diagram. We demonstrate that the HO phase at finite fields can be explained with a chiral dxy+idx2-y2 spin density wave, assuming that the zero field HO contains only the time-reversal symmetry preserving idx2-y2 component. We argue that the presence of the field-induced chiral HO can be reflected in a distinctive non-linear B-dependence of the Kerr angle, when a Kerr experiment is conducted for finite fields. This fingerprint can be conclusive for the possible emergence of chirality in the HO.