Non-ohmic Hall effect as a novel probe for unconventional transport in the pseudogap regime of copper-oxide superconductors

Description

The pseudogap temperature range above the critical temperature T_c in underdoped copper-oxide superconductors has attracted a great deal of attention for many years and exhibits a plethora of unusual phenomena. Many theoretical approaches strive for explaining the findings of various experiments. Still, the disagreement between theoretical models demonstrates vividly the need for additional experimental probes. Since a non-linear current-voltage dependence is one hallmark of closing the superconducting energy gap, one might expect to see such phenomena in the pseudogap regime, too. Along these lines, we explore a novel experimental approach, the investigation of resistivity and Hall effect in the normal state of underdoped YBa₂Cu₃O_6+x (YBCO) beyond the weak electric field limit and the search for possible non-ohmic effects. However, above T_c, the samples are in a resistive state and at the required high current densities, thermal heating effects make simple current-voltage measurements impossible. To overcome these limitations, we use a pulsed-current technique to reduce sample heating and a thermal model to estimate the latter. The Hall conductivity turns out to provide the best experimental access to the non-linear transport properties. Its weak temperature dependence in the pseudogap regime makes it less susceptible to Joule heating effects that cannot be fully ruled out. Our measurements add a novel boundary to the phase diagram of YBCO at various doping levels, which is briefly discussed regarding theoretical models.

Period	13 Oct 2021
Event title	Low dimensional superconducting hybrids for novel quantum functionalities
Event type	Conference
Location	Paris, FranceShow on map
Degree of Recognition	International