Disorder raises the critical temperature of a cuprate superconductor

The origin of high-temperature superconductivity remains poorly understood to date. Over the past two decades, spatial oscillations of the electronic density known as charge-density waves (CDWs) have been found to coexist with high-temperature superconductivity in most prominent cuprate superconductors. The debate on whether CDWs help or hinder high-temperature superconductivity in cuprates is still ongoing. In principle, disorder at the atomic scale should strongly suppress both high-temperature superconductivity and CDWs. In this work, however, we find that disorder created by irradiation increases the superconducting critical temperature by 50% while suppressing the CDW order, showing that CDWs strongly hinder bulk superconductivity. We show that this increase occurs because the CDWs could be frustrating the superconducting coupling between atomic planes.

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Image:  In an ideal system, orthogonal charge-spin stripes in adjacent layers prevent Josephson coupling between layers. Left: In the presence of disorder, distorted stripes around defects are not orthogonal, which reestablishes Josephson coupling between layers and increases TC.