The breakdown of both strange metal and superconducting states at a pressure-induced quantum critical point in iron-pnictide superconductors.

Cai, Shu; Zhao, Jinyu; Ni, Ni; Guo, Jing; Yang, Run; Wang, Pengyu; Han, Jinyu; Long, Sijin et al. · Nat Commun · 2023

basic_science · Level V

Where this comes from

Abstract

Here we report the first observation of the concurrent breakdown of the strange metal (SM) normal state and superconductivity at a pressure-induced quantum critical point in Ca<sub>10</sub>(Pt<sub>4</sub>As<sub>8</sub>)((Fe<sub>0.97</sub>Pt<sub>0.03</sub>)<sub>2</sub>As<sub>2</sub>)<sub>5</sub> superconductor. We find that, upon suppressing the superconducting state, the power exponent (α) changes from 1 to 2, and the slope of the temperature-linear resistivity per FeAs layer (A<sup>□</sup>) gradually diminishes. At a critical pressure, A<sup>□</sup> and superconducting transition temperature (T<sub>c</sub>) go to zero concurrently, where a quantum phase transition from a superconducting state with a SM normal state to a non-superconducting Fermi liquid state occurs. Scaling analysis reveals that the change of A<sup>□</sup> with T<sub>c</sub> obeys the relation of T<sub>c</sub> ~ (A<sup>□</sup>)<sup>0.5</sup>, similar to what is seen in other chemically doped unconventional superconductors. These results suggest that there is a simple but powerful organizational principle of connecting the SM normal state with the high-T<sub>c</sub> superconductivity.