Dynamical charge density fluctuations, isotropic scattering and anomalous metallic behaviour

Dynamical charge density fluctuations, isotropic scattering and anomalous metallic behaviour

C. Di Castro

Accademia dei Lincei; Department of Phisics, University of Roma “Sapienza”,
Pazza A. Moro Roma I-00185
[email protected].

The recent RIXS (high-resolution resonant inelastic X-ray scattering) experiments have given a new impulse to the physics of cuprates [1]. In particular, the newly discovered short-range dynamical charge density fluctuations account for the strange metal behaviour of the cuprates [2]. Due to their broadness, charge density fluctuations mediate an almost isotropic scattering among the fermi quasiparticles. For temperatures greater than their characteristic energy specified by the inverse correlation length and by the dissipation parameter, this scattering provides the famous linear-in-T resistivity. The linearity and a seemingly divergent specific heath [3], are extended to the lowest temperatures by an increase of the damping of the fluctuations while the correlation length stays finite [4], thus providing the so called Planckian behavior. Namely in ref. [4], we are proposing a new paradigm in contrast with the standard hot-spot model. Usually, the diverging correlation length is invoked to produce quantum criticality and perhaps anomalous metallic behaviour, here the strange-metal behaviour with linear resistivity and a diverging specific heat occurring near QCPs can be attributed to and accounted for by the increase of the damping parameter only.
Remarkably, this isotropic scattering has been now confirmed in the Planckian regime [5].

References

[1] R. Arpaia, S. Caprara, R. Fumagalli, G. De Vecchi, Y.Y. Peng, E. Andersson, D. Betto, G. M. De Luca, N. B. Brookes, F. Lombardi, M. Salluzzo, L. Braicovich, C. Di Castro, M. Grilli, G. Ghiringhelli, Dynamical charge density fluctuations pervading the phase diagram of a copper-based high-Tc superconductor, Science 365, 906 (2019)
[2] G. Seibold, R. Arpaia, Y. Y. Peng, R. Fumagalli, L. Braicovich, C. Di Castro, M. Grilli, G. Ghiringhelli, and S. Caprara, Strange metal behaviour from charge density fluctuations in cuprates, Commun. Phys. 4, 7 (2021).
[3] Michon, B., Girod, C., Badoux, S., Kamar´ık, J., Ma, Q. Dragomir, M., Dabkowska, H. A., Gaulin, B. D., Zhou, J.-S., Pyon, S., Takayama, T., Takagi, H., Verret, S., Doiron Leyraud, N., Marcenat, C., Taillefer, L. & Klein, T., Thermodynamic signatures of quantum criticality in cuprate superconductors, Nature 567, 218222 (2019)
[4] S. Caprara, C. Di Castro, G. Mirarchi, G. Seibold and M. Grilli
Dissipation-driven strange metal behavior, arXiv-2012.11697 21 Dec 2020
[5] G. Grissonnanche, Yawen Fang, A. Legros, S. Verret, F. Laliberté, C. Collignon, J. Zhou, D. Graf, P. A. Goddard, L. Taillefer and B. J. Ramshaw, Linear-in temperature resistivity from an isotropic Planckian scattering rate. Nature 595, 667 (2021)