Disorder from order among anisotropic next-nearest-neighbor Ising spin chains in SrHo$_2$O$_4$

TL;DR

This study investigates how competing interactions in SrHo₂O₄ lead to coexisting ordered and disordered spin chains, revealing the role of topological defects in preventing full magnetic order at low temperatures.

Contribution

It demonstrates the coexistence of ordered and disordered spin chains in SrHo₂O₄ and highlights the impact of topological defects on magnetic ordering.

Findings

Néel chains develop 3D long-range order below 0.68 K.

Double-Néel chains remain disordered below 0.52 K.

Topological defects hinder full magnetic order in the system.

Abstract

We describe why Ising spin chains with competing interactions in $\rm SrHo_2O_4$ segregate into ordered and disordered ensembles at low temperatures ($T$). Using elastic neutron scattering, magnetization, and specific heat measurements, the two distinct spin chains are inferred to have N\'eel ($\uparrow\downarrow\uparrow\downarrow$) and double-N\'eel ($\uparrow\uparrow\downarrow\downarrow$) ground states respectively. Below $T_\mathrm{N}=0.68(2)$~K, the N\'eel chains develop three dimensional (3D) long range order (LRO), which arrests further thermal equilibration of the double-N\'eel chains so they remain in a disordered incommensurate state for $T$ below $T_\mathrm{S}= 0.52(2)$~K. $\rm SrHo_2O_4$ distills an important feature of incommensurate low dimensional magnetism: kinetically trapped topological defects in a quasi$-d-$dimensional spin system can preclude order in $d+1$ dimensions.