Giant magnetothermal conductivity and magnetostriction effect in charge ordered Nd${}_{0.8}$Na${}_{0.2}$MnO${}_3$ compound

We present results on resistivity ($\rho$), magnetization ($M$), thermal conductivity ($\kappa$), magnetostriction ($\frac{\mathrm{\Delta }L}{L(0)}$) and specific heat ($C_p$) of charge-orbital ordered antiferromagnetic Nd${}_{0.8}$Na${}_{0.2}$MnO${}_3$ compound. Magnetic field-induced antiferromagnetic/charge-orbital ordered insulating to ferromagnetic metallic transition leads to giant magnetothermal conductivity and magnetostriction effect. The low-temperature irreversibility behavior in $\rho$, $M$, $\kappa$ and $\frac{\mathrm{\Delta }L}{L(0)}$ due to field cycling together with striking similarity among the field and temperature dependence of these parameters manifest the presence of strong and complex spin-charge-lattice coupling in this compound. The giant magnetothermal conductivity is attributed mainly to the suppression of phonon scattering due to the destabilization of spin fluctuations and static/dynamic Jahn-Teller distortion by the application of magnetic field.