The Nernst effect and the boundaries of the Fermi liquid picture

Dynamic Superconductivity Responses in Photo-excited Optical Conductivity and Nernst Effect

High-Tc cuprate, A3C60 and other unconventional superconductors (SCs) have very high Tc with respect to the energy scale of superconducting (SC) charges inferred from the superfluid density (SFD). The observed linear dependence of Tc on the SFD can hardly be expected in BCS SCs while being reminiscent of Bose Einstein Condensation of pre-formed pairs. As additional non-BCS like behaviors, responses similar to those in the bulk SC states have been observed at temperatures (T) well above Tc in the vortex-like Nernst effect, diamagnetic susceptibility, and transient optical conductivity in photo-…

Band-dependent normal-state coherence in Sr$_{2}$RuO$_{4}$: Evidence from Nernst effect and thermopower measurements

We present the first measurement on Nernst effect in the normal state of odd-parity, spin-triplet superconductor Sr$_{2}$RuO$_{4}$. Below 100 K, the Nernst signal was found to be negative, large, and, as a function of magnetic field, nonlinear. Its magnitude increases with the decreasing temperature until reaching a maximum around $T^*$ $\approx$ 20 - 25 K, below which it starts to decrease linearly as a function of temperature. The large value of the Nernst signal appears to be related to the multiband nature of the normal state and the nonlinearity to band-dependent magnetic fluctuation in S…

Nernst quantum oscillations in bulk semi-metals

With a widely available magnetic field of 10 T, one can attain the quantum limit in bismuth and graphite. At zero magnetic field, these two elemental semi-metals host a dilute liquid of carriers of both signs. When the quantum limit is attained, all quasi-particles are confined to a few Landau tubes. Each time a Landau tube is squeezed before definitely leaving the Fermi surface, the Nernst response sharply peaks. In bismuth, additional Nernst peaks, unexpected in the non-interacting picture, are resolved beyond the quantum limit. The amplitude of these unexpected Nernst peaks is larger in the…

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 p…

Hidden Fermi Liquid, Scattering Rate Saturation and Nernst Effect: a DMFT Perspective

We investigate the transport properties of a correlated metal within dynamical mean field theory. Canonical Fermi liquid behavior emerges only below a very low temperature scale $T_{FL}$. Surprisingly the quasiparticle scattering rate follows a quadratic temperature dependence up to much higher temperatures and crosses over to saturated behavior around a temperature scale $T_{sat}$. We identify these quasiparticles as constituents of the hidden Fermi liquid. The non-Fermi liquid transport above $T_{FL}$, in particular the linear-in-$T$ resistivity, is shown to be a result of a strongly tempera…

有隙节面驱动手性晶格反铁磁体中的大拓扑能斯特效应

Gapped nodal planes drive a large topological Nernst effect in a chiral lattice antiferromagnet

本文结合热电输运实验与含六百余个Wannier轨道的模型，揭示CoNb3S6中有隙节面产生的涌现磁场热点驱动大自发能斯特效应。