Planckian Dissipation and non-Ginzburg-Landau Type Upper Critical Field in Bi2201

TL;DR

This study investigates the resistivity and upper critical field in Bi2201, revealing Planckian dissipation and a novel temperature dependence of Hc2 that suggests uncondensed Cooper pairs exist above the critical field.

Contribution

It presents experimental evidence of Planckian dissipation and introduces a new temperature dependence of the upper critical field in Bi2201, challenging Ginzburg-Landau theory.

Findings

Linear temperature dependence of resistivity in high magnetic fields.

Linear scattering rate consistent with Planckian dissipation.

A new form of Hc2(T) indicating uncondensed Cooper pairs.

Abstract

Resistivity and Hall effect measurements have been carried out on a micro-fabricated bridge of Bi2201 single crystal at low temperatures down to 0.4 K under high magnetic fields. When superconductivity is crashed by a high magnetic field, the recovered "normal state" resistivity still shows a linear temperature dependence in low temperature region. Combining with the effective mass and the charge carrier density, we get a linear scattering rate $1/\tau = \alpha k_{B} T/\hbar$ with $0.77<\alpha<1.16$, which gives a strong evidence of the Planckian dissipation. Furthermore, our results reveal a new type of temperature dependence of upper critical field, $H_{c2}(T)=H^*\sqrt{(1-t)/(t+0.154)}$, which is totally different from the expectation of the Ginzburg-Landau theory, and suggests uncondensed Cooper pairs above $H_{c2}(T)$ line.