Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators
We investigate the effect of magnon–magnon interactions on the dispersion and polarization of magnon modes in collinear antiferromagnetic (AF) insulators at finite temperatures. In two-sublattice AF systems with uniaxial easy-axis and biaxial easy-plane magneto-crystalline anisotropies, we implement...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2022-01-01
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| Series: | New Journal of Physics |
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| Online Access: | https://doi.org/10.1088/1367-2630/ac94f0 |
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| author | Mahroo Shiranzaei Roberto E Troncoso Jonas Fransson Arne Brataas Alireza Qaiumzadeh |
| author_facet | Mahroo Shiranzaei Roberto E Troncoso Jonas Fransson Arne Brataas Alireza Qaiumzadeh |
| author_sort | Mahroo Shiranzaei |
| collection | DOAJ |
| description | We investigate the effect of magnon–magnon interactions on the dispersion and polarization of magnon modes in collinear antiferromagnetic (AF) insulators at finite temperatures. In two-sublattice AF systems with uniaxial easy-axis and biaxial easy-plane magneto-crystalline anisotropies, we implement a self-consistent Hartree–Fock mean-field approximation to explore the nonlinear thermal interactions. The resulting nonlinear magnon interactions separate into two-magnon intra- and interband scattering processes. Furthermore, we compute the temperature dependence of the magnon bandgap and AF resonance modes due to nonlinear magnon interactions for square and hexagonal lattices. In addition, we study the effect of magnon interactions on the polarization of magnon modes. We find that although the noninteracting eigenmodes in the uniaxial easy-axis case are circularly polarized, but in the presence of nonlinear thermal interactions the U(1) symmetry of the magnon Hamiltonian is broken. The attractive nonlinear interactions squeeze the low energy magnon modes and make them elliptical. In the biaxial easy-plane case, on the other hand, the bare eigenmodes of low energy magnons are elliptically polarized but thermal nonlinear interactions squeeze them further. Direct measurements of the predicted temperature-dependent AF resonance modes and their polarization can be used as a tool to probe the nonlinear interactions. Our findings establish a framework for exploring the effect of thermal magnon interactions in technologically important magnetic systems, such as magnetic stability of recently discovered two-dimensional magnetic materials, coherent transport of magnons, Bose–Einstein condensation of magnons, and magnonic topological insulators. |
| first_indexed | 2024-03-12T16:03:24Z |
| format | Article |
| id | doaj.art-32350efc31024289aaef5a6bb5e4cf2a |
| institution | Directory Open Access Journal |
| issn | 1367-2630 |
| language | English |
| last_indexed | 2024-03-12T16:03:24Z |
| publishDate | 2022-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | New Journal of Physics |
| spelling | doaj.art-32350efc31024289aaef5a6bb5e4cf2a2023-08-09T14:27:20ZengIOP PublishingNew Journal of Physics1367-26302022-01-01241010300910.1088/1367-2630/ac94f0Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulatorsMahroo Shiranzaei0Roberto E Troncoso1Jonas Fransson2Arne Brataas3Alireza Qaiumzadeh4Department of Physics and Astronomy, Division of Materials Theory, Uppsala University , Box 516, SE-75120 Uppsala, SwedenDepartment of Physics, Center for Quantum Spintronics, Norwegian University of Science and Technology , NO-7491 Trondheim, Norway; School of Engineering and Sciences, Universidad Adolfo Ibáñez , Santiago, ChileDepartment of Physics and Astronomy, Division of Materials Theory, Uppsala University , Box 516, SE-75120 Uppsala, SwedenDepartment of Physics, Center for Quantum Spintronics, Norwegian University of Science and Technology , NO-7491 Trondheim, NorwayDepartment of Physics, Center for Quantum Spintronics, Norwegian University of Science and Technology , NO-7491 Trondheim, NorwayWe investigate the effect of magnon–magnon interactions on the dispersion and polarization of magnon modes in collinear antiferromagnetic (AF) insulators at finite temperatures. In two-sublattice AF systems with uniaxial easy-axis and biaxial easy-plane magneto-crystalline anisotropies, we implement a self-consistent Hartree–Fock mean-field approximation to explore the nonlinear thermal interactions. The resulting nonlinear magnon interactions separate into two-magnon intra- and interband scattering processes. Furthermore, we compute the temperature dependence of the magnon bandgap and AF resonance modes due to nonlinear magnon interactions for square and hexagonal lattices. In addition, we study the effect of magnon interactions on the polarization of magnon modes. We find that although the noninteracting eigenmodes in the uniaxial easy-axis case are circularly polarized, but in the presence of nonlinear thermal interactions the U(1) symmetry of the magnon Hamiltonian is broken. The attractive nonlinear interactions squeeze the low energy magnon modes and make them elliptical. In the biaxial easy-plane case, on the other hand, the bare eigenmodes of low energy magnons are elliptically polarized but thermal nonlinear interactions squeeze them further. Direct measurements of the predicted temperature-dependent AF resonance modes and their polarization can be used as a tool to probe the nonlinear interactions. Our findings establish a framework for exploring the effect of thermal magnon interactions in technologically important magnetic systems, such as magnetic stability of recently discovered two-dimensional magnetic materials, coherent transport of magnons, Bose–Einstein condensation of magnons, and magnonic topological insulators.https://doi.org/10.1088/1367-2630/ac94f0magnonantiferromagnetthermal squeezingmagnon–magnon interactionnonlinear effectuniaxial and biaxial antiferromagnet |
| spellingShingle | Mahroo Shiranzaei Roberto E Troncoso Jonas Fransson Arne Brataas Alireza Qaiumzadeh Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators New Journal of Physics magnon antiferromagnet thermal squeezing magnon–magnon interaction nonlinear effect uniaxial and biaxial antiferromagnet |
| title | Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators |
| title_full | Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators |
| title_fullStr | Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators |
| title_full_unstemmed | Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators |
| title_short | Thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators |
| title_sort | thermal squeezing and nonlinear spectral shift of magnons in antiferromagnetic insulators |
| topic | magnon antiferromagnet thermal squeezing magnon–magnon interaction nonlinear effect uniaxial and biaxial antiferromagnet |
| url | https://doi.org/10.1088/1367-2630/ac94f0 |
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