Total suppression of superconductivity by high magnetic fields in YBa2 Cu3O6.6

TL;DR

This study investigates how high magnetic fields suppress superconductivity in underdoped YBCO6.6 crystals, revealing that superconducting fluctuations can be fully suppressed at very high fields, with disorder affecting phase coherence.

Contribution

It demonstrates total suppression of superconductivity by high magnetic fields in underdoped YBCO6.6 and explores the effects of disorder on phase coherence and pseudogap properties.

Findings

Superconducting fluctuations are suppressed at 50 Tesla in pure YBCO6.6.

Disorder reduces phase coherence and affects the onset of the Nernst signal.

Normal state magnetoresistance is restored above a threshold field H'c(T).

Abstract

We have studied in fields up to 60T the variation of the transverse magnetoresistance (MR) of underdoped YBCO6.6 crystals either pure or with Tc reduced down to 3.5K by electron irradiation. We evidence that the normal state MR is restored above a threshold field H'c(T), which is found to vanish at T'c>>Tc. In the pure YBCO6.6 sample a 50 Tesla field is already required to completely suppress the superconducting fluctuations at Tc. While disorder does not depress the pseudogap temperature, it reduces drastically the phase coherence established at Tc and weakly H'c(0), T'c and the onset Tnu of the Nernst signal which are more characteristic of the 2D local pairing.