Strange Metal: Planckian Dissipation
T-linear resistivity and the Planckian scattering rate τ⁻¹ = k_BT/ℏ
Strange metals (non-Fermi liquids) show T-linear resistivity ρ(T)=ρ₀+AT across wide temperature ranges.
The scattering rate saturates the "Planckian bound": τ⁻¹ = α·k_BT/ℏ with α∼1.
This is the fastest possible scattering (uncertainty principle: ΔE·τ≥ℏ/2, ΔE∼k_BT).
In conventional Fermi liquids, ρ∝T² from electron-electron scattering.
The strange metal phase is observed in cuprate superconductors above T_c, heavy fermion compounds near
quantum critical points, and twisted bilayer graphene — suggesting a universal quantum critical mechanism.