Magnetic multilayers of alternating Weyl and Skyrmionic topologies are highly sought for novel device technology due to the possibility of efficiently manipulating magnetic textures and realizing phenomena such as the quantum anomalous Hall effect. In magnetic Weyl semimetals, the electronic band structure features pairs of Weyl nodes with opposite chirality charges, and the momentum space position of these nodes can reverse across a planar interface, giving rise to Fermi-arc-like bound states. We use a low-energy approximation to show that a magnetic interstitial layer can tune these states in three distinct ways: the electrostatic potential and in-plane magnetic potential components control the shape of the bound-state Fermi-arcs, with moderate in-plane magnetic potentials spin-filtering electrons across the interface1. Additionally, both in-plane magnetic components and electrostatic potentials regulate electron transmission, while the ratio of in-plane to out-of-plane magnetic components modulates magnetic potential effects. This tunability stems from spin-momentum locking and chirality reversal at the interface, allowing for a material-dependent interchange of states. Our model can be universally extended to investigate 2D planar twinning interfaces in B20 compounds using first-principles calculations, focusing on the Weyl semimetal CoGe2 with a FeGe3 interstitial. By employing supercell calculations that restrict the interface to the primitive cell, we demonstrate that the spin and anomalous Hall effects are significantly enhanced due to increased spin-orbit coupling and atomic potential variations at the interface. We explore the interplay between nonmagnetic Weyl semimetals and magnetic skyrmion-hosting systems in heterostructures across two thickness regimes: one with a semi-infinite Weyl system and a thin skyrmion-hosting film and the other with a semi-infinite skyrmion system and a thin Weyl film. This work defines the physical bounds of skyrmion-Weyl interactions and determines methods to maximize the synergy of these two systems.
References:
1. Thareja, E., Pantano, G., Vekhter, I. & Gayles, J. Tuning Quantum States at Chirality-Reversed Planar Interface in Weyl Semimetals using an Interstitial Layer. (2025).
2. Spencer, C. S. et al. Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20 Fe1−𝑦Co𝑦Ge films. Phys. Rev. B 97, 214406 (2018).
3. Gayles, J. et al. Dzyaloshinskii-Moriya Interaction and Hall Effects in the Skyrmion Phase of Mn1−𝑥Fe𝑥Ge. Phys. Rev. Lett. 115, 036602 (2015).