Heat capacity measurements of Sr₂RuO₄ under uni-axial strain

One of the most-discussed possible pairing symmetries of Sr₂RuO₄ is p_x ± ip_y. By applying strain along left angle 100 right angle -direction, the degeneracy of the p_x and p_y components is lifted, and thus there should be two critical temperatures (T_c). Hicks et al. have observed an increase of T_c of Sr₂RuO₄ under both compressive and tensile strains, by measuring the susceptibility, which is sensitive only to the first transition. Their results also indicate, indirectly, that any splitting of T_cs might be small. For a direct test of possible splitting, we measure the heat capacity of Sr₂RuO₄ under strain. To do so, we are developing an approach to measure heat capacity under non-adiabatic conditions. We have observed an increase of T_c under compressive strain. This is the first thermodynamic evidence of the strain-induced increase in T_c of Sr₂RuO₄.