Evidence for a quantum phase transition in electron-doped Pr$_{2-x}$Ce$_{x}$CuO$_{4-\delta}$ from Thermopower measurements

TL;DR

This study provides thermopower measurements in electron-doped Pr$_{2-x}$Ce$_{x}$CuO$_{4- ext{delta}}$ that support the existence of a quantum phase transition from antiferromagnetic to paramagnetic states near x=0.16, clarifying a controversial aspect of high-$T_c$ cuprates.

Contribution

It offers new thermopower data that corroborate the quantum phase transition in electron-doped cuprates, linking thermopower behavior to magnetic state changes.

Findings

Thermopower and S/T increase dramatically from x=0.11 to 0.16.

Behavior mirrors Hall effect results in the same material.

Supports a quantum phase transition near x=0.16.

Abstract

The evidence for a quantum phase transition under the superconducting dome in the high-$T_c$ cuprates has been controversial. We report low temperature normal state thermopower(S) measurements in electron-doped Pr$_{2-x}$Ce$_{x}$CuO$_{4-\delta}$ as a function of doping (x from 0.11 to 0.19). We find that at 2K both S and S/T increase dramatically from x=0.11 to 0.16 and then saturate in the overdoped region. This behavior has a remarkable similarity to previous Hall effect results in Pr$_{2-x}$Ce$_{x}$CuO$_{4-\delta}$ . Our results are further evidence for an antiferromagnetic to paramagnetic quantum phase transition in electron-doped cuprates near x=0.16.