Giant thermoelectric power factor anisotropy in PtSb${}_{1.4}$Sn${}_{0.6}$

We report giant anisotropy in thermoelectric power factor ($S^2\sigma$) of marcasite structure-type PtSb${}_{1.4}$Sn${}_{0.6}$. PtSb${}_{1.4}$Sn${}_{0.6}$, synthesized using ambient pressure flux growth method upon mixing Sb and Sn on the same atomic site, is a new phase different from both PtSb${}_2$ and PtSn${}_2$ that crystallize in the cubic $Pa\bar{3}$ pyrite and $Fm\bar{3}m$ fluorite unit cell symmetry, respectively. Giant difference in $S^2\sigma$ for heat flow applied along different principal directions of the orthorhombic unit cell mostly stems from anisotropic Seebeck coefficients.