Unconventional critical behavior in quasi-one-dimensional $S$ = 1 chain NiTe$_{2}$O$_{5}$

TL;DR

This study introduces NiTe$_{2}$O$_{5}$, a new quasi-one-dimensional $S$=1 chain compound, revealing its unique antiferromagnetic order and unconventional critical behavior at low temperatures.

Contribution

The paper reports the discovery and detailed characterization of NiTe$_{2}$O$_{5}$, highlighting its novel magnetic order and critical phenomena distinct from typical antiferromagnets.

Findings

Long-range antiferromagnetic order at 30.5 K

Unconventional critical exponents with $eta\,\sim0.18$

Magnetic moments exhibit mixed ferromagnetic and antiferromagnetic couplings

Abstract

Here we report a new quasi-one-dimensional $S$ = 1 chain compound NiTe$_{2}$O$_{5}$. From the comprehensive study of the structure and magnetic properties on high quality single crystalline NiTe$_{2}$O$_{5}$, it's revealed that NiTe$_{2}$O$_{5}$ undergoes a transition into an intriguing long-range antiferromagnetic order at $T_{\rm N}=30.5 {\rm K}$, in which longitudinal magnetic moments along the chain direction are ferromagnetically ordered, while their transverse components have an alternating ferromagnetic-antiferromagnetic coupling. Even though the temperature dependence of magnetic susceptibility represents an archetypal anisotropic antiferromagnetic order, we found that critical behavior of unconventional nature with $\alpha'\sim0.25$ and $\beta\sim0.18$ is accompanied by the temperature evolution of the antiferromagnetic order parameter.