Antisymmetric magnetoresistance in Fe3GeTe2 nanodevices of inhomogeneous thickness

With the emergence of the van der Waals two-dimensional (2D) ferromagnetic materials, Fe3GeTe2 (FGT) with a high Curie temperature (T-C) and the perpendicular magnetic anisotropy (PMA) provides a rich platform for the next generation spintronic devices. Up to now, in most 2D magnets-based devices, the easiest and the most convenient way to obtain thin flakes is still the mechanical exfoliation method. However, samples with thickness variation occur inevitably during this process, which are either ignored due to the thicknessinhomogeneity-induced complicated phenomena or far from been fully reached. Herein, unlike conventional symmetric magnetoresistance with respect to the magnetic field observed in thickness-uniform FGT flakes, we demonstrate a hitherto rarely observed antisymmetric magnetoresistance in thickness-inhomogeneous nanodevices. Since the T-C and coercive field (H-C) of FGT are thickness dependent, thickness variations in FGT flake lead to different regions with distinct H(C)s. Together with the thickness variations-induced differences in H(C)s and the PMA, an eddy current generates in the proximity of the thickness boundary during the magnetic switching process. This eddy current perturbs the longitudinal resistance and results in the unexpected antisymmetry. Our work provides a new understanding and the device application in thickness-variation 2D ferromagnetic materials, which are more experimentally common but have been neglected thus far.

Automated summary

This study explores the rarely observed antisymmetric magnetoresistance in thickness-inhomogeneous nanodevices compared to the symmetric magnetoresistance in thickness-uniform samples. Variations in thickness lead to distinct coercive fields in different regions, generating eddy currents near the thickness boundary during magnetic switching and causing unexpected antisymmetry in longitudinal resistance. This work provides insights and potential device applications in thickness-variation 2D ferromagnetic materials that have been overlooked in previous research.