Universal saturation of electron dephasing in three-dimensional disordered metals

Abstract

We have systematically investigated the low-temperature electron dephasing times $τ_ϕ$ in more than 40 three-dimensional polycrystalline impure metals with distinct material characteristics. In all cases, a saturation of the dephasing time is observed below about a (few) degree(s) Kelvin, depending on samples. The value of the saturated dephasing time $τ_0$ [$\equiv τ_ϕ(T \to 0 {\rm K})$] falls basically in the range 0.005 to 0.5 ns for all samples. Particularly, we find that $τ_0$ scales with the electron diffusion constant $D$ as $τ_0 \sim D^{- α}$, with $α$ close to or slightly larger than 1, for over two decades of $D$ from about 0.1 to 10 cm$^2$/s. Our observation suggests that the saturation behavior of $τ_ϕ$ is universal and intrinsic in three-dimensional polycrystalline impure metals. A complete theoretical explanation is not yet available.