Manipulating the Nernst effect in RuO2 thin films by crystal symmetry

Thermoelectric conversion through the Nernst effect holds great promise for energy-harvesting scenarios. Typically, the applied thermal gradient, magnetic field and the generated voltage V are mutually orthogonal to induce a B-linear out-of-plane Nernst effect. Here, we show that this restriction can be lifted by engineering proper crystal orientation in RuO2 films. While RuO2 (100) and RuO2 (110) are consistent with normal circumstances, we observe a B-linear planar Nernst effect (LPNE) in RuO2 (101). This is attributed to the low symmetry RuO2 (101) crystal lattice that allows for a non-zero off-diagonal component in the Nernst coefficient tensor. In addition, we find that the magnitude for the LPNE is stable across the temperature range of 60–280 K, with fluctuation <±13.5%, which surpasses the temperature stability for conventional Nernst effects. Our work advances the understanding of crystal symmetry-modulated thermoelectric phenomenon, providing a feasible approach to manipulate the Nernst effects.