Proposal for All-Electrical Skyrmion Detection in van der Waals Tunnel Junctions

Dongzhe Li (1) , Soumyajyoti Haldar (2) , Stefan Heinze (2)

1 CEMES - Centre d'élaboration de matériaux et d'études structurales
2 CAU - Christian-Albrechts-Universität zu Kiel = Christian-Albrechts University of Kiel = Université Christian-Albrechts de Kiel

A major challenge for magnetic skyrmions in atomically thin van der Waals (vdW) materials is reliable skyrmion detection. Here, based on rigorous first-principles calculations, we show that all-electrical skyrmion detection is feasible in 2D vdW magnets via scanning tunneling microscopy (STM) and in planar tunnel junctions. We use the nonequilibrium Green's function method for quantum transport in planar junctions, including self-energy due to electrodes and working conditions, going beyond the standard Tersoff-Hamann approximation. We obtain a very large tunneling anisotropic magnetoresistance (TAMR) around the Fermi energy for a vdW tunnel junction based on graphite/Fe 3 GeTe 2 /germanene/graphite. For atomic-scale skyrmions the noncollinear magnetoresistance (NCMR) reaches giant values. We trace the origin of the NCMR to spin-mixing between spin-up and-down states of p z and d z 2 character at the surface atoms. Both TAMR and NCMR are drastically enhanced in tunnel junctions with respect to STM geometry due to orbital symmetry matching at the interface.

Mots clés: Spintronics; Magnetic skyrmions; Quantum transport; Noncollinear magnetoresistance; van der Waals tunnel junctions

Domaines: Matière Condensée [cond-mat]

Dongzhe Li, Soumyajyoti Haldar, Stefan Heinze. Proposal for All-Electrical Skyrmion Detection in van der Waals Tunnel Junctions. Nano Letters, In press, ⟨10.1021/acs.nanolett.3c04238⟩. ⟨hal-04458778⟩