Universal behavior in the Nernst effect of heavy fermion materials

We report the observation of a universal scaling of the Nernst coefficient over a wide intermediate temperature range in heavy fermion materials, including the superconductors CeCu$_2$Si$_2$, CeCoIn$_5$, and Ce$_2$PdIn$_8$, the ferromagnetic Kondo lattice Ce$_3$RhSi$_3$, the nonmagnetic CeRu$_2$Si$_2$, the intermediate valent YbAl$_3$, and the hidden order compound URu$_2$Si$_2$, that cover a broad spectrum of heavy fermion materials with different crystal, valence and ground state properties. The scaling formula follows exactly the magnetic susceptibility of emergent heavy quasiparticles as predicted in the two-fluid model. We give a tentative explanation of the scaling based on the skew scattering mechanism and the Boltzmann picture and argue that the Nernst effect is produced by the asymmetry of the quasiparticle density of states rather than that of the scattering rate. In URu$_2$Si$_2$, the giant Nernst signal in the hidden order phase is also found to follow the predicted scaling, indicating the potential involvement of hybridization physics. Our work suggests a candidate unified scenario for the Nernst effect in heavy fermion materials.