11 June 2024

Magnon-phonon interactions enhance the gap at the Dirac point in the spin-wave spectra of CrI3 two-dimensional magnets

CrI3 is attracting wide scientific interest because it is the first compound reported to display long-range magnetic order down to the monolayer limit. Here, it behaves as a ferromagnetic semiconductor with a Curie temperature of 45 K and a sizable out-of-plane anisotropy.

<<Building upon our previous work on the gap between the two magnonic branches at the Dirac point, we reveal through ab initio calculations a robust magnon-phonon coupling for vibrational modes in proximity to the Dirac point's magnon gap.>> says Oscar Baseggio (SISSA, Italy) one of the authors of the paper.

In this study, researchers evaluate the strength of these couplings and insert them in an interacting magnon-phonon Hamiltonian featuring a linear coupling between lattice and spin fluctuations. << Our model shows how the magnon-phonon close coupling can give rise to mixed magnon-phonon modes somewhat analogous to polaritons in polar dielectrics and be responsible for enhancing the gap in the range of ≈4 meV around the Dirac point of the CrI3 monolayer.>> continues Baseggio.

Calculations were performed using one of the MaX lighthouse codes, Quantum ESPRESSO. This work partly stems from the Quantum ESPRESSO feature extension program within the MaX project. The study has widely benefited from using the experimental GPU-accelerated versions of the suite. Thanks to the MaX effort, all these features and HPC implementation are currently part of the production version of Quantum ESPRESSO and available to all users.


About Quantum ESPRESSO
Quantum ESPRESSO  is the major open-source (set of) code(s) for quantum materials modelling using the plane-wave pseudopotential method. It has been the development platform for such important methodological innovations as Car-Parrinello molecular dynamics and Density-Functional Perturbation Theory.


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