Evidence for a generic novel quantum transition in high-Tc cuprates

TL;DR

This study provides experimental evidence for a novel quantum transition in high-Tc cuprates, marked by abrupt magnetic changes and singular spin fluctuation slowing at a critical doping, dividing the superconducting phase into two distinct ground states.

Contribution

It reveals a previously unidentified quantum transition in high-Tc superconductors, characterized by magnetic spectrum changes and spin fluctuation behavior at a critical doping.

Findings

Abrupt changes in magnetic spectrum at critical doping

Singular slowing down of spin fluctuations at T=0

Evidence for two distinct ground states in the phase diagram

Abstract

We study the low-energy spin fluctuations and superfluid density of a series of pure and Zn-substituted high-$T_c$ superconductors (HTS) using the muon spin relaxation and $ac$-susceptibility techniques. At a critical doping state, $p_c$, we find (i) simultaneous abrupt changes in the magnetic spectrum in the superconducting ground state and (ii) that the slowing down of spin fluctuations becomes singular at T=0. These results provide experimental evidence for a novel quantum transition that separates the superconducting phase diagram of HTS into two distinct ground states.