A hydrodynamic description for transport in the strange metal phase of cuprates*

High temperature superconductors are strongly coupled systems which makes it difficult to isolate the mechanism governing their singular transport properties. In strongly coupled systems one generically expects short equilibration times meaning that only long lived degrees of freedom are important. Hydrodynamics is the framework for describing such degrees of freedom. Because hydrodynamics mostly relies on the symmetries of the system, without referring to any specific microscopic mechanism, it constitutes a promising approach for analysing these materials.

In this talk I will argue that in the strange metal phase of the cuprates, a whole set of transport coefficients are described by a universal hydrodynamic framework [1]. We will subsequently corroborate our theoretical prediction against experimental data for the DC transport properties of Bi-2201 close to optimal doping. In particular, we characterise all the DC transport properties of a given sample for several crystals. Integral to our hydrodynamic description is the inclusion of the pseudo-spontaneous breaking of translation invariance, one manifestation of which is charge density waves [2].

Recently, we have managed to additionally obtain the AC electric conductivity for the same crystals used in the DC transport measurements described above. I will conclude by discussing the implications of this new data for our hydrodynamic model.

[1] A. Amoretti et al., Phys. Rev. Research 2, 023387 (2020).

[2] Peng, Y. Y. et al. Nature Materials 17, 697–702 (2018).