Fluctuations and all-in$-$all-out ordering in dipole-octupole Nd2Zr2O7

TL;DR

This study investigates the magnetic properties of Nd2Zr2O7, revealing a transition to an all-in-all-out antiferromagnetic state at very low temperatures and highlighting its unique dipolar-octupolar magnetic nature.

Contribution

It provides the first detailed experimental characterization of Nd2Zr2O7's magnetic phase diagram and uncovers its unconventional magnetic behavior linked to dipolar-octupolar moments.

Findings

Transition to all-in-all-out antiferromagnetic order at 285 mK

Metamagnetic transition around 0.1 T

Reduced ordered magnetic moment and non-standard magnetization curves

Abstract

We present an experimental study of the pyrochlore coumpound Nd2Zr2O7 by means of neutron scattering and magnetization measurements down to 90 mK. The Nd$^{3+}$ magnetic moments exhibit a strong local $\langle$111$\rangle$ Ising anisotropy together with a dipolar-octupolar nature, different from the standard Kramers-doublet studied so far. We show that, despite the positive Curie-Weiss temperature, \ndzr\ undergoes a transition around 285 mK towards an all-in$-$all-out antiferromagnetic state. We establish the $(H,T)$ phase diagram in the three directions of the applied field and reveal a metamagnetic transition around 0.1 T. The strongly reduced ordered magnetic moment as well as the unexpected shape of the magnetization curves demonstrate that Nd2Zr2O7 , is not a standard Ising antiferromagnet. We propose that the peculiar nature of the Nd doublet combined with competing interactions explain these findings.