{23}Na nuclear spin-lattice relaxation studies of Na2Ni2TeO6

TL;DR

This study uses {23}Na NMR to investigate the magnetic properties of Na2Ni2TeO6, revealing critical divergence near the Neel temperature and indicating three-dimensional magnetic behavior despite low-dimensional susceptibility features.

Contribution

It provides detailed NMR analysis of critical magnetic behavior and phase transition characteristics in Na2Ni2TeO6, highlighting three-dimensional critical phenomena.

Findings

Critical divergence of 1/{23}T_1 near T_N=26 K

Identification of a narrow critical region

Evidence of three-dimensional magnetic critical behavior

Abstract

We report on {23}Na NMR studies of a honeycomb lattice antiferromagnet Na2Ni2TeO6 by {23}Na nuclear spin-echo techniques. The {23}Na nuclear spin-lattice relaxation rate 1/{23}T_1 exhibits critical divergence near a Neel temperature T_N = 26 K, a narrow critical region, and a critical exponent w = 0.34 in 1/{23}T_1 = a (T/T_N - 1)^{-w} for Na2Ni2TeO6, and T_N = 18 K for Na2(Ni{0.5}Cu{0.5})2TeO6. Although the uniform magnetic susceptibility of Na2Ni2TeO6 exhibits a broad maximum at 35 K characteristic of low dimensional spin systems, the NMR results indicate three dimensional critical phenomenon around the Neel temperature.