Planckian dissipation and non-Ginzburg-Landau type upper critical field in Bi2201

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 the low temperature region. Combining with the effective mass and the charge carrier density, we get a linear scattering rate 1/ τ = αk B T / ħ with 0.77 < α < 1.16, which gives a strong evidence of the Planckian dissipation. Furthermore, our results reveal a new type of temperature dependence of the upper critical field, H c 2 ( T ) = H ∗ ( 1 − t ) / ( t + 0.154 ) , which is totally different from the expectation of the Ginzburg-Landau theory, and suggests the existence of uncondensed Cooper pairs above H c 2 ( T ) line.