Theoretical study on the anomalies of the magnetic susceptibility in the honeycomb lattice compound Na2Co2TeO6

In this paper, based on ab initio molecular dynamics and the exchange-interaction model, the magnetic order transition phenomenon of ${\mathrm{Na}}₂{\mathrm{Co}}₂\mathrm{Te}{\mathrm{O}}₆$ material under different temperatures is investigated. Our results exclude the effect of lattice distortion as a factor for magnetic susceptibility under different temperatures in ${\mathrm{Na}}₂{\mathrm{Co}}₂\mathrm{Te}{\mathrm{O}}₆$. Furthermore, we found that the charge transfer is not a main factor to effectively explain the magnetic phase transition. We proposed a method based on radial distribution function to analyze the space-charge density (SCD) to explore the thermal fluctuations. Our analysis of SCD implies that the thermal fluctuations induced by the variation of atomic vibration under different temperatures are responsible for the anomalies of magnetic susceptibility in ${\mathrm{Na}}₂{\mathrm{Co}}₂\mathrm{Te}{\mathrm{O}}₆$ below the N\'eel temperature.