Although the occurrence of charge density wave (CDW) order in underdoped cuprates is a well-established phenomenon, the role of CDW in superconductivity (SC) is still an intensely debated topic. Notably, the observed suppression of SC is drastically different between two similar cuprates La2-xSrxCuO4 and La2-xBaxCuO4 at 1/8 doping. In LBCO 1/8, SC is taken over completely by static CDW, while in LSCO 1/8, SC is only slightly suppressed. Some have pointed to the low-temperature crystal symmetry being accountable for this difference. Namely, the low temperature tetragonal (LTT) lattice distortion that occurs concomitant with the appearance of CDW order can pin CDW and influence the superconducting ground state. We used coherent resonant x-ray speckle correlation analysis and directly determined the temperature hysteresis of CDW domain for LBCO 1/8. We observed consistently reproducible CDW domain textures upon repeated temperature cycling well above the 54 K CDW/LTT transition before the domains are dramatically reconfigured by cycling over 240(3) K. This associates CDW domain texture pinning with the low temperature orthorhombic (LTO) structural phase transition rather than disorder or the LTT structural transition. Our observation provides a new view into the complex intertwining of charge and lattice degrees of freedom in forming the superconducting ground state.
Chen received her BS in Engineering Physics from Cornell University, and her Ph.D in physics from the University of Illinois at Urbana-Champaign with focus on applying x-ray scattering to strongly correlated systems. Chen then joined the X-ray Scattering Group at Brookhaven National Lab as a postdoctoral research associate to focus on using coherent soft x-ray to study transition metal oxides. She is currently a postdoc at Lawrence Berkeley Lab studying frustrated magnets. Chen's research interest includes studying strongly correlated materials using coherent x-ray scattering and imaging with emphasis on effects of disorder and quantum confinement.