Magnetic structure and low temperature properties of geometrically frustrated SrNd$_2$O$_4$

TL;DR

This study investigates the low-temperature magnetic properties of SrNd$_2$O$_4$, revealing partial magnetic order, site-specific magnetic moments, and a field-induced phase transition, advancing understanding of geometrically frustrated magnetism.

Contribution

The paper provides the first detailed neutron diffraction analysis of SrNd$_2$O$_4$, showing partial magnetic order and disordered sites, and maps its magnetic phase diagram under applied fields.

Findings

Magnetic order appears below 2.28 K with an extit{A}FM state.

Only one Nd$^{3+}$ site exhibits a significant magnetic moment.

A phase transition occurs around 30 kOe in an applied magnetic field.

Abstract

We report the low-temperature properties of SrNd$_2$O$_4$, a geometrically frustrated magnet. Magnetisation and heat capacity measurements performed on polycrystalline samples indicate the appearance of a magnetically ordered state at $T_{\rm N}=2.28(4)$~K. Powder neutron diffraction measurements reveal that an \afm\ state with the propagation vector \QV\ is stabilised below this temperature. The magnetic order is incomplete, as only one of the two Nd$^{3+}$ sites carries a significant magnetic moment while the other site remains largely disordered. The presence of a disordered magnetic component below $T_{\rm N}$ is confirmed with polarised neutron diffraction measurements. In an applied magnetic field, the bulk properties measurements indicate a phase transition at about 30~kOe. We construct a tentative $H$-$T$ phase diagram of \sno\ from these measurements.