Experimental evidence that zinc impurities pin pair-density-wave order in La2-xBaxCuO4

Both Zn doping and c-axis magnetic fields have been observed to increase the spin stripe order in La2-xBaxCuO4 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.