# Condensed Matter Seminars

**Condensed Matter**

Thursday, December 9, 2021

3:30 PM

Online, Room via Zoom

Note special room.

## "T-linear resistivity down to T→0 at the pseudogap critical point of holed-doped cuprates and Planckian dissipation "

**Dr. Anaelle Legros , John Hopkins University**

[Host: Utpal Chatterjee]

: 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_{B}T (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}_{−}* _{x}*Nd

_{0.4}Sr

*CuO*

_{x}_{4}, 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)

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