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

Dongzhe Li; Soumyajyoti Haldar; Stefan Heinze

doi:10.1021/acs.nanolett.3c04238

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

Nano Lett. 2024 Feb 28;24(8):2496-2502. doi: 10.1021/acs.nanolett.3c04238. Epub 2024 Feb 13.

Authors

Dongzhe Li¹, Soumyajyoti Haldar², Stefan Heinze^{2

3}

Affiliations

¹ CEMES, Université de Toulouse, CNRS, 29 rue Jeanne Marvig, F-31055 Toulouse, France.
² Institute of Theoretical Physics and Astrophysics, University of Kiel, Leibnizstrasse 15, 24098 Kiel, Germany.
³ Kiel Nano, Surface and Interface Science (KiNSIS), University of Kiel, 24118 Kiel, Germany.

PMID: 38350134
DOI: 10.1021/acs.nanolett.3c04238

Abstract

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 two-dimensional 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 graphite/Fe₃GeTe₂/germanene/graphite vdW tunnel junction. 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_z² 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.

Keywords: magnetic skyrmions; noncollinear magnetoresistance; quantum transport; spintronics; van der Waals tunnel junctions.