IDENTIFICATION OF A NEMATIC PAIR DENSITY WAVE STATE IN Bi2Sr2CaCu2O8+x

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We thank these Agencies for Research Support

Published Article (Proc. Nat'l Acad. Sci. 119, 2206481119 - July 2022)

Electron-pair density wave (PDW) states are now an intense focus of research in the field of cuprate correlated superconductivity. PDW's exhibit periodically modulating superconductive electron pairing which can be visualized directly using scanned Josephson tunneling microscopy (SJTM). Although from theory, intertwining the d-wave superconducting (DSC) and PDW order parameters allows a plethora of global electron-pair orders to appear, which one actually occurs in the various cuprates is unknown. We used SJTM to visualize the interplay of PDW and DSC states in Bi2Sr2CaCu2O8+x at a carrier density where the charge density wave (CDW) modulations are virtually nonexistent. Simultaneous visualization of their amplitudes reveals that the intertwined PDW and DSC are mutually attractive states. Then, by separately imaging the electron-pair density modulations of the two orthogonal PDWs, we discover a robust nematic PDW state. Its spatial arrangement entails Ising domains of opposite nematicity, each consisting primarily of unidirectional and lattice commensurate electron-pair density modulations. Further, we demonstrate directly that the Ising domains of the nematic PDW state are pinned by Zn impurity atoms.