Unconventional Dynamical Scaling close to a Nematic Quantum Critical Point

ORAL

Abstract

In the vicinity of quantum critical points, the complex interplay between electronic and structural order can lead to a vast range of highly unconventional phases. Of particular interest is the electronic nematic order, with its predicted long-range interactions mediated through the lattices shear modes. Here, we report an unusual scaling relation of the magnetoresistivity in the iron-based superconductor FeSe0.89S0.11 when tuned to its nematic quantum critical point under hydrostatic pressure. We observe a remarkably sharp crossing over two decades in temperature, which fulfills a power-law scaling relation with diverging critical exponents at low temperatures, in stark contrast to the usual fixed exponent ansatz. We discuss our findings in the context of disconnected static and dynamic quantum fluctuations, a coupling between electronic and phononic modes, and topological changes of the Fermi surface. These lead to the emergence of an atypical non-zero energy scale at the quantum critical point which strongly affects superconductivity.

*We acknowledge funding by the EPSRC (EP/I004475/1, EP/ I017836/1, EP/M020517/1), the NSF (DMR-1157490, DMR-1828489), the State of Florida, the John Fell Fund of Oxford University and the Oxford Centre for Applied Superconductivity.

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Presenters

  • Pascal Reiss

    • Clarendon Laboratory, University of Oxford

Authors

  • Pascal Reiss

    • Clarendon Laboratory, University of Oxford

  • David E Graf

    • National High Magnetic Field Laboratory
    • Florida State University
    • National High Magnetic Field Lab, Florida State University
    • National High Magnetic Field Laboratory, Tallahassee and Florida State University
    • National High Magnetic Field Laboratory, Florida State University
    • National High Magnetic Field Laboratory (FSU)
    • Department of Physics, Florida State University
    • National High Magnetic Field Laboratory and Department of Physics, Florida State University
    • National High Magnetic Field Lab
    • National High Magnetic Field Laboratory, Tallahassee, FL
    • CMS, National High Magnetic Laboratory

  • Amir-Abbas Haghighirad

    • Karlsruhe Institute of Technology
    • Institute for Quantum Materials and Technologies, Karlsruhe Institute of Technology

  • Thomas Vojta

    • Missouri University of Science & Technology
    • Department of Physics, Missouri University of Science and Technology

  • Amalia Coldea

    • Clarendon Laboratory, University of Oxford