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Terahertz Magnetospectroscopy Evidence of Spin-Magnon Interactions in the Low-Temperature Phase Transition of Erbium Orthoferrites

ORAL

Abstract

Magnonic excitations in antiferromagnets can couple with degrees of freedom coming from the same magnetic system, such as spins. This interaction resembles that of two-level atoms cooperatively interacting with a single mode of light, where a superradiant phase transition (SRPT) is theoretically predicted to occur as the coupling strength is increased. To date, a SRPT in thermal equilibrium has not been realized experimentally, and it has been shown that charged particles will remain stable against it. However, there remains a strong possibility to observe a phase transition analogous to the SRPT in magnetically ordered systems, where spins instead of charges interact with a common quantum field, which would then provide new insights into the original photon SRPT. In this work, we studied Er1-xYxFeO3 as a function of temperature, magnetic field, and Y composition (x) through terahertz time-domain magnetospectroscopy. Magnon excitations showed drastic spectral changes as the system undergoes a phase transition at low temperatures. We demonstrate that this phase transition can be modeled by an extended Dicke Hamiltonian taking into account long-range Er-Fe and short-range Er-Er interactions on an equal footing.

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Presenters

  • Nicolas Marquez Peraca

    Rice University, Rice Univ, Department of Physics and Astronomy, Rice University

Authors

  • Nicolas Marquez Peraca

    Rice University, Rice Univ, Department of Physics and Astronomy, Rice University

  • Motoaki Bamba

    Kyoto University, Department of Physics, Kyoto University

  • Kenji Hayashida

    Rice University, Division of Applied Physics, Hokkaido University

  • Xinwei Li

    Rice University, Department of Physics, California Institute of Technology, Department of Electrical and Computer Engineering, Rice University

  • Xiaoxuan Ma

    Shanghai University, Department of Physics, Shanghai University

  • Takuma Makihara

    Department of Physics and Astronomy, Rice University

  • Diego Fallas Padilla

    Department of Physics and Astronomy, Rice University

  • Chien-Lung Huang

    Rice Univ, Department of Physics and Astronomy, Rice University

  • Emilia Morosan

    Rice Univ, Department of Physics and Astronomy and Rice Center for Quantum Materials, Rice Univ, Rice University, Department of Physics and Astronomy, Rice University

  • Han Pu

    Rice Univ, Department of Physics and Astronomy, Rice University

  • Shixun Cao

    Shanghai University, Department of Physics, Shanghai University

  • Junichiro Kono

    Electrical and Computer Engineering, Rice University, Department of Electrical and Computer Engineering, Rice Univ, Rice University, Rice Univ, Department of Electrical and Computer Engineering, Rice University, Department of Physics and Astronomy, Rice University