Field-induced quantum critical route to a Fermi liquid in high-temperature superconductors

TL;DR

This study reveals a magnetic field-driven transition from non-Fermi-liquid to Fermi-liquid behavior in an overdoped high-T_c superconductor, indicating a quantum critical point near the upper critical field with implications for understanding correlated electron systems.

Contribution

It demonstrates a field-induced quantum critical transition in a cuprate superconductor, linking it to heavy-Fermion systems and suggesting a common spin-related physics mechanism.

Findings

Fermi-liquid behavior appears above a critical magnetic field

Critical field decreases linearly with temperature

Fermi-liquid coefficient diverges near the quantum critical point

Abstract

In high transition temperature (T_c) superconductivity, charge doping is a natural tuning parameter that takes copper oxides from the antiferromagnet to the superconducting region. In the metallic state above T_c the standard Landau's Fermi-liquid theory of metals as typified by the temperature squared (T^2) dependence of resistivity appears to break down. Whether the origin of the non-Fermi-liquid behavior is related to physics specific to the cuprates is a fundamental question still under debate. We uncover a new transformation from the non-Fermi- to a standard Fermi-liquid state driven not by doping but by magnetic field in the overdoped high-T_c superconductor Tl_2Ba_2CuO_{6+x}. From the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid features appear above a sufficiently high field which decreases linearly with temperature and lands at a quantum critical point near the superconductivity's upper critical field -- with the Fermi-liquid coefficient of the T^2 dependence showing a power-law diverging behavior on the approach to the critical point. This field-induced quantum criticality bears a striking resemblance to that in quasi-two dimensional heavy-Fermion superconductors, suggesting a common underlying spin-related physics in these superconductors with strong electron correlations.