Experimental Evidence that Zn Impurities Pin Pair-Density-Wave Order in La$_{2-x}$Ba$_x$CuO$_4$

TL;DR

This study demonstrates that Zn impurities in La$_{2-x}$Ba$_x$CuO$_4$ pin pair-density-wave order, leading to enhanced 2D and 3D superconductivity, revealing the role of impurities in modulating complex electronic orders.

Contribution

It provides experimental evidence that Zn impurities can locally pin pair-density-wave order in cuprates, a novel insight into impurity effects on competing electronic phases.

Findings

Zn doping induces 2D superconductivity in La$_{2-x}$Ba$_x$CuO$_4$

Zn impurities pin pair-density-wave order locally

Superconductivity transitions from 2D to 3D at lower temperatures

Abstract

Both Zn-doping and $c$-axis magnetic fields have been observed to increase the spin stripe order in La$_{2-x}$Ba$_x$CuO$_4$ with $x$ close to 1/8. For $x=0.095$, the applied magnetic field also causes superconducting layers to decouple, presumably by favoring pair-density-wave order that consequently frustrates interlayer Josephson coupling. Here we show that introducing 1% Zn also leads to an initial onset of two-dimensional (2D) superconductivity, followed by 3D superconductivity at lower temperatures, even in zero field. We infer that the Zn pins pair-density-wave order locally, establishing the generality of such behavior.