A recent high-energy x-ray diffraction experiment, led by Prof. Johan Chang’s group, provides a new insight into the relationship between superconductivity and adjacent charge density wave (CDW) phase in YBa2Cu3O6.67 (YBCO). The three-dimensional CDW order competes stronger with superconductivity than its two-dimensional counterpart. This effect was directly observed by exploring the phase competition in a momentum space. On this basis, an interpretation of a spatially inhomogeneous superconducting state was put forward. The competition induced inhomogeneity generates a strong and fragile superconducting flavor, providing an experimental test-bed for several theoretical proposals for competing orders.
This experiment was carried out in PETRA III synchrotron of DESY (Hamburg, Germany) through an international collaboration of 11 research institutes in 7 different countries including Switzerland, Germany, and the United Kingdom. In particular, a 17 Tesla magnet for x-ray scattering experiments, developed by the group in the University of Birmingham, was indispensable for this study.
 J. Choi et al.; Nature Communications 11, 990 (2020)