Abstract
After a brief review of current ideas on stripe order in cuprate high-temperature superconductors, we discuss the quasiparticle Nernst effect in cuprates, with focus on its evolution in non-superconducting stripe and related nematic states. In general, we find the Nernst signal to be strongly enhanced by nearby van-Hove singularities and Lifshitz transitions in the band structure, implying that phases with translation symmetry breaking often lead to a large quasiparticle Nernst effect due to the presence of multiple small Fermi pockets. Open orbits may contribute to the Nernst signal as well, but in a strongly anisotropic fashion. We discuss our results in the light of recent proposals for a specific Lifshitz transition in underdoped YBa2Cu3Oy and make predictions for the doping dependence of the Nernst signal.
Highlights
After a brief review of current ideas on stripe order in cuprate high-temperature superconductors, we discuss the quasiparticle Nernst effect in cuprates, with focus on its evolution in non-superconducting stripe and related nematic states
Recent Nernst measurements on underdoped cuprates have revealed additional information: in stripe-ordered La1.6−x Nd0.4Srx CuO4 the temperature dependence of the Nernst signal shows an additional peak or shoulder at intermediate temperatures, which was tentatively attributed to a Fermi-surface reconstruction due to density-wave order [17]. (Note that this interpretation has been questioned by others [18])
The Nernst response has been calculated in simple quasiparticle models, and it has been shown that density-wave order can lead to an enhanced Nernst signal [22]–[26], with the sign depending on the spatial periodicity and other details of the ordering pattern [25]
Summary
After a brief review of current ideas on stripe order in cuprate high-temperature superconductors, we discuss the quasiparticle Nernst effect in cuprates, with focus on its evolution in non-superconducting stripe and related nematic states. In de-twinned crystals of YBa2Cu3Oy (YBCO), the normal-state Nernst signal was found to be negative [19] and to display a huge temperature-dependent in-plane anisotropy [20] The latter fact appears to tie in with the tendency to electron-nematic order, previously identified in neutron-scattering measurements on YBCO-6.45 [21]. While small Fermi pockets induce a strongly enhanced Nernst signal in both directions, open orbits appreciably contribute to the Nernst response only for a temperature gradient applied parallel to the dominant hopping direction This allows specific predictions for the normal-state Nernst signal across the Lifshitz transition
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