Condensed Matter Seminars

: The perfectly linear temperature dependence of the resistivity observed as T→0 in a variety of metals close to a quantum critical point is a major puzzle of condensed matter physics. In cuprates, this phenomenon is observed in the vicinity of the pseudogap critical point p*. Using high magnetic fields to suppress superconductivity, one can access the normal state properties down to T→0 close to this critical point. I will present high-field magneto-transport measurements of two hole-doped cuprates, near their respective p*, supporting that T-linear resistivity as T→0 is a generic property of cuprates, associated with a universal scattering rate. We measured the low-T resistivity of Bi2Sr2CaCu2O8+δ just above p* [1] and found that it exhibits a T-linear dependence, quantitatively similar to other very different cuprates. We also observed, using the Drude formula, that in various cuprates showing this low-T phenomenon the slope of this T-linear resistivity is given by a universal relation implying a specific scattering rate for charge carriers: 1/�� = αh/2πk_BT (corresponding to what is called the Planckian limit [2]), where h is Planck’s constant, k_B is the Boltzmann constant and α a constant of order unity. Finally, we directly measured the scattering rate in La_1.6−xNd_0.4Sr_xCuO₄, just above p* and in the low-T limit, using angle-dependent magneto-resistance measurements [4]: these experiments reveal an inelastic scattering rate which is isotropic and linear in temperature, and whose magnitude is consistent with Planckian dissipation.
[1] Legros et al., Nat. Phys. 15, 142 (2019)
[2] Zaanen, SciPost Phys. 6, 061 (2019)
[3] Grissonnanche et al., Nature 595, 667 (2021)