Anisotropic magneto-Seebeck effect in the antiferromagnetic semimetal FeGe2

We have investigated thermoelectric properties of the antiferromagnetic semimetal $\mathrm{Fe}{\mathrm{Ge}}₂$. As temperature decreases from 340 K, the Seebeck coefficient takes a maximum around the N\'eel temperature and then decreases to show a sign change from positive to negative 50 K. When a strong magnetic field is applied perpendicular to the sample plane, the sign change disappears, and the positive Seebeck coefficient is observed in the whole temperature range. This large magneto-Seebeck effect is anisotropic since the Seebeck coefficient is insensitive to in-plane magnetic fields. Based on the Mott formula, we discuss the origins for this anisotropic magneto-Seebeck effect.