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

Abstract

We describe why Ising spin chains with competing interactions in $\mathrm{SrH}{\mathrm{o}}_2{\mathrm{O}}_4$ 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 Néel ($\uparrow \downarrow \uparrow \downarrow$) and double-Néel ($\uparrow \uparrow \downarrow \downarrow$) ground states respectively. Below $T_{\mathrm{N}}=0.68(2)$~K, the Néel chains develop three dimensional (3D) long range order (LRO), which arrests further thermal equilibration of the double-Néel chains so they remain in a disordered incommensurate state for $T$ below $T_{\mathrm{S}}=0.52(2)$~K. $\mathrm{SrH}{\mathrm{o}}_2{\mathrm{O}}_4$ 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.

10 pages, 10 figures