Effect of impurities on the Néel temperature and the low-temperature magnetic susceptibility of the quasi-one-dimensional antiferromagnet TMMC

Abstract

Low-temperature magnetic susceptibility and N\'eel-temperature measurements of tetramethylammonium trichloromanganate (TMMC) doped by different impurities, Cd, Cu, Co, and Ni, are reported. For TMMC: Cd, an additional susceptibility proportional to ${T}^{\ensuremath{-}1}$ above ${T}_{N}$ and a drastic reduction of ${T}_{N}$ by a factor of 2 for Cd concentration as low as 0.5 at.% have been observed. These features are well explained by assuming complete breaking of the Mn antiferromagnetic chains. Both susceptibility and ${T}_{N}$ measurements in TMMC with magnetic impurities have demonstrated the existence of an impurity-Mn interaction ${J}_{1}$ and allowed its estimation: ${J}_{1\mathrm{C}\mathrm{u}\ensuremath{-}\mathrm{M}\mathrm{n}}=1.4$ K and $|{J}_{1\mathrm{N}\mathrm{i}\ensuremath{-}\mathrm{M}\mathrm{n}}|=1.9$ K. We give experimental evidence of the $\mathrm{XY}$ behavior of the one-dimensional correlations at low temperature.