Double-layered monopolar order in Tb2Ti2O7 spin liquid

TL;DR

This paper reveals a novel double-layered monopolar order in Tb2Ti2O7 spin liquid under high magnetic field, contrasting with monopole-free behavior in related spin ices, through neutron diffraction and symmetry analysis.

Contribution

It introduces the concept of double-layered monopolar order in Tb2Ti2O7 and re-analyzes its magnetic structure using a monopole framework and symmetry considerations.

Findings

Tb2Ti2O7 orders as a double-layered monopole-antimonopole structure under high field.

Contrasts the monopole-free state of Ho2Ti2O7 in similar conditions.

Provides symmetry-based distortions compatible with the observed magnetic structure.

Abstract

Ho2Ti2O7 and Dy2Ti2O7 spin ices exhibit elementary excitations akin to magnetic monopoles. Here we focus on Tb2Ti2O7 spin liquid, where correlated magnetic moments keep fluctuating down to very low temperatures. Using a monopole picture, we have re-analyzed the field-induced magnetic structure previously determined by neutron diffraction in Tb2Ti2O7. We show that under a high field applied along a [110] direction, Tb2Ti2O7 orders as a three dimensional arrangement of monopole and antimonopole double layers. In contrast, Ho2Ti2O7 spin ice in the same conditions behaves as a monopole-free state. By symmetry analysis we derived the distortions compatible with the observed magnetic structure of Tb2Ti2O7 which can be related to the appearance of the double-layered monopolar order.