arXiv subjects

Bilal Jabakhanji

Publications and source records attributed to Bilal Jabakhanji.

5 recordsLinked to original sources

arXiv2026

Topological Magnon-Phonon Hybrid Bands in Ferromagnetic Skyrmion Crystals

We investigate magnon-phonon (MP) excitations in a Neel-type two-dimensional ferromagnetic skyrmion crystal (SkX) stabilized on a triangular spin lattice by Dzyaloshinskii-Moriya interaction (DMI). Although the lowest two magnon bands of the bare SkX are topologically trivial, we show that coupling to lattice vibrations reconstructs the low-energy sector and generates topological MP hybrid bands. Starting from a spin-lattice Hamiltonian in which phonons couple to magnons through fluctuations of the DMI vectors, we derive the bosonic Hamiltonian for the SkX and compute the hybrid band structure by Bogoliubov diagonalization. MP coupling opens gaps at low-energy magnon-phonon crossings, lifts phonon degeneracies associated with supercell folding, and yields nontrivial Chern numbers for the lowest hybrid bands. The resulting low-energy topology and associated edge states remain robust under magnetic-field variation, while higher-energy hybrid bands can undergo field-driven topological phase transitions. These results extend topological magnon-phonon hybridization to noncoplanar SkXs.

cond-mat.mes-hall↗

arXiv2026

Impact of the honeycomb spin-lattice on topological magnons and edge states in ferromagnetic 2D skyrmion crystals

Magnons have been intensively studied in two-dimensional (2D) ferromagnetic (FM) skyrmion crystals (SkXs) stabilized on Bravais lattices, particularly triangular and square lattices. In these systems, topological edge states (TESs) have been reported in higher-energy magnon gaps, while the first magnon gap is found to be topologically trivial. In this context, antiferromagnetic (AFM) SkXs on the triangular spin lattice have been considered potentially more interesting for applications, since TESs emerge already in the first magnon gap. Meanwhile, the magnon topology of SkXs stabilized on non-Bravais spin lattices remains largely unexplored. In this work, we theoretically investigate the magnon band structure and TESs in 2D FM SkXs stabilized on the honeycomb spin lattice, including experimentally motivated parameter sets relevant to van der Waals magnets. We show that chiral TESs emerge in the first magnon gap over significant ranges of the Dzyaloshinskii-Moriya interaction and single-ion magnetic anisotropy. Magnetic-field-driven topological phase transitions modify the number of these TESs before eventually trivializing them. In addition, we find that TESs can coexist in the first and higher magnon gaps, which could enable frequency-multiplexed magnonic edge transport. These findings highlight the role of lattice geometry in shaping the magnon topology and edge transport in noncollinear spin textures.

cond-mat.mes-hall↗

arXiv2024

Momentum-space theory for topological magnons in 2D ferromagnetic skyrmion lattices

Magnon dynamics in skyrmion lattices have garnered significant interest due to their potential applications in topological magnonics. Existing theories often follow a single-momentum approach, assuming significant Dzyaloshinskii-Moriya Interaction (DMI) to minimize the skyrmion's dimensions, which can lead to oversimplification in describing magnon behavior. This study introduces a multi-momentum operator theory for magnons in large 2D skyrmions, where each skyrmion encompasses several thousand spins. The proposed theory fully transforms the magnon Hamiltonian into momentum space, incorporating off-diagonal terms to capture umklapp scattering caused by the skyrmion wave vectors. Our results reveal deviations from single-momentum theories, demonstrating that flat bands are not universal features of the skyrmionic magnon spectrum. Additionally, we find that manipulating the skyrmion size with an external magnetic field induces multiple topological phase transitions. At high magnetic fields, the low-energy magnon spectrum becomes densely packed and entirely topological, resembling a topological band continuum.

cond-mat.mes-hall↗

arXiv2023

Designing layered 2D skyrmion lattices in moiré magnetic hetero-structures

Skyrmions are promising for the next generation of spintronic and magnonic devices, but their zero-field stability and controlled nucleation through chiral interactions remain challenging. In this theoretical study, we explore the potential of moiré magnetic heterostructures to generate ordered skyrmion lattices from the stacking-dependent magnetism in 2D magnets. We consider heterostructures formed by twisting ultrathin CrBr_3 films on top of CrI_3 substrates, assuming a moderate interfacial Dzyaloshinskii-Moriya interaction. At large moiré periodicity and appropriate substrate thickness, a moiré skyrmion lattice emerges in the interfacial CrBr_3 layer due to the weaker exchange interactions in CrBr_3 compared to CrI_3. This lattice is then projected to the remaining layers of the CrBr_3 film via emergent chiral interlayer fields. By varying the pristine stacking configurations within the ultrathin CrBr_3 film, we realize layered ferromagnetic and antiferromagnetic skyrmion lattices without the need for a permanent magnetic field. Our findings suggest the possibility of creating colorful skyrmion lattices in moiré magnetic heterostructures, enabling further exploration of their fundamental properties and technological relevance.

cond-mat.mtrl-sci↗

arXiv2022

Whirling interlayer fields as a source of stable topological order in moiré CrI3

The moiré engineering of two-dimensional magnets opens unprecedented opportunities to design novel magnetic states with promises for spintronic device applications. The possibility of stabilizing skyrmions in these materials without chiral spin-orbit couplings or dipolar interactions is yet to be explored. Here, we investigate the formation and control of ground state topological spin textures (TSTs) in moiré CrI3 using stochastic Landau-Lifshitz-Gilbert simulations. We unveil the emergence of interlayer vortex and antivortex Heisenberg exchange fields, stabilizing spontaneous and field-assisted ground state TSTs with various topologies. The developed study accounts for the full bilayer spin dynamics, thermal fluctuations, and intrinsic spin-orbit couplings. By examining the effect of the Kitaev interaction and the next nearest-neighbor Dzyaloshinskii-Moriya interaction, we propose the latter as the unique spin-orbit coupling mechanism compatible with experiments on monolayer and twisted CrI3. Our findings contribute to the current knowledge about moiré skyrmionics and uncover the nature of spin-orbit coupling in CrI3.

cond-mat.mtrl-sci↗