The lamellar cuprate superconductors exhibit the highest ambient-pressure superconducting transition temperatures (Tc), and after more than three decades of extraordinary research activity, continue to pose formidable scientific challenges. A major experimental obstacle has been to distinguish universal phenomena from materials- or technique-dependent ones. Angle-resolved photoemission spectroscopy (ARPES) measures momentum-dependent single-particle electronic excitations and has been invaluable in the endeavor to determine the anisotropic momentum-space properties of the cuprates. HgBa2CuO4+δ (Hg1201) is a single-CuO2-layer cuprate with a particularly high optimal Tc and a simple crystal structure, yet there exists little information from ARPES about the electronic properties of this model system. Here we present an ARPES study of doping-, temperature-, and momentum-dependent systematics of near-nodal dispersion anomalies in Hg1201. The data reveal a hierarchy of three distinct energy scales: a subgap low-energy kink, an intermediate-energy kink near 55 meV, and a peak-dip-hump structure. The first two features are attributed to the coupling of electrons to Ba-derived optical phonons and in-plane bond-stretching phonons, respectively. The nodal peak-dip-hump structure appears to have a common doping dependence in several single-layer cuprates and is interpreted as a manifestation of pseudogap physics at the node. These results establish several universal phenomena, both in terms of connecting multiple experimental techniques for a single material and in terms of connecting comparable spectral features in multiple structurally similar cuprates.
Bibliographical noteFunding Information:
The authors acknowledge helpful discussions with Andrey Chubukov, Tom Devereaux, Zhenglu Li, Dmitry Reznik, and B. Sriram Shastry. Work at UC Davis was supported by AFOSR Grant No. FA9550-18-1-0156. Work at the University of Minnesota was funded by the Department of Energy through the University of Minnesota Center for Quantum Materials under DE-SC0016371. Work at UC Berkeley and Lawrence Berkeley Laboratory was supported by the Office of Science, Office of Basic Energy Sciences (BES), Materials Sciences and Engineering Division of the U.S. Department of Energy (DOE) under Contract No. DE-AC02-05-CH1231 within the Quantum Materials Program (KC2202). Work at Rice University was supported by the Robert A. Welch Foundation Grant No. C-2024 and the Alfred P. Sloan Foundation FG-2019-12224. Use of the Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. This research used resources of the Advanced Light Source, a DOE Office of Science User Facility under Contract No. DE-AC02-05CH11231.
© 2020 American Physical Society.