Fig. 3: Néel-type skyrmions observed by Lorentz transmission electron microscopy.

a Schematic diagram of a Néel-type skyrmion on a tilt sample for Lorentz transmission electron microscopy imaging. The orange and blue circles are for positive and negative magnetizations along z direction, respectively. Brown arrows indicate the in-plane magnetization component while gray arrows indicate the Lorentz force. b Lorentz transmission electron microscopy observation of skyrmion lattice from under focus to over focus on WTe₂/40L Fe₃GeTe₂ samples at 180 K with a field of 510 Oe. Scale bar: 500 nm. c Lorentz transmission electron microscopy observation of a Néel-type skyrmion at T = 94 K, α = 21.86° and H = 540, 600 Oe, where α is the angle between the sample plane and xy plane. The yellow arrow points to a skyrmion. The skyrmion size is  ~150 nm. Scale bar: 500 nm. d Simulation results considering a finite depth of interfacial Dzyaloshinskii–Moriya interaction in Fe₃GeTe₂.