Susceptibility anisotropy and absence of ferroelectric order in the Kitaev spin liquid candidate Na2Co2TeO6

Abstract

We report the magnetic, magnetodielectric, and electric polarization properties of single crystals of the Co-based Kitaev Spin Liquid (KSL) candidate Na${}_2$Co${}_2$TeO${}_6$ (NCTO). The sample shows magnetic transitions at 26 K, 16 K, and 5 K, consistent with the literature. The magnetic measurements along and perpendicular to the Co-honeycomb planes show a strong anisotropy in susceptibility and in Curie-Weiss (C - W) temperatures. The experimental anisotropic C-W temperatures of NCTO qualitatively match with the theoretical C-W temperatures, calculated by using the HK$\Gamma {\Gamma }^{\prime }$ model. We find from our temperature and field dependent dielectric and pyroelectric ($I_p$) current studies ($H\left|\right|ab$ and $E\perp ab$) that our single crystal NCTO samples do not have a finite electric polarization below 100 K. These $I_p$ studies confirm the absence of a magneto-electric coupling and electric polarization properties in the title compound and suggest that the zig-zag AFM structure is more favorable than the triple-Q structure with AFM Kitaev interactions.