Room-temperature skyrmion lattice in a layered magnet (Fe _0.5 Co _0.5 ) ₅ GeTe ₂

Abstract

Novel magnetic ground states have been stabilized in two-dimensional (2D) magnets such as skyrmions, with the potential next-generation information technology. Here, we report the experimental observation of a Néel-type skyrmion lattice at room temperature in a single-phase, layered 2D magnet, specifically a 50% Co–doped Fe 5 GeTe 2 (FCGT) system. The thickness-dependent magnetic domain size follows Kittel’s law. The static spin textures and spin dynamics in FCGT nanoflakes were studied by Lorentz electron microscopy, variable-temperature magnetic force microscopy, micromagnetic simulations, and magnetotransport measurements. Current-induced skyrmion lattice motion was observed at room temperature, with a threshold current density, j th = 1 × 10 6 A/cm 2 . This discovery of a skyrmion lattice at room temperature in a noncentrosymmetric material opens the way for layered device applications and provides an ideal platform for studies of topological and quantum effects in 2D.

Room‐Temperature Magnetic Skyrmions and Large Topological Hall Effect in Chromium Telluride Engineered by Self‐Intercalation

“…[1] Since the discovery of intrinsic 2D magnetism in van der Waals (vdW) materials, [17,18] layered magnets have become attractive platforms for spintronics. Magnetic skyrmions have been successfully created in Cr 2 Ge 2 Te 6 , Fe 3 GeTe 2 , and Fe 5 GeTe 2 , [13,[19][20][21][22][23] whereas the room-temperature THE were rarely reported. Recent studies reported the THE-like bumps and dips in Fe 3 GeTe 2 , [24,25] while it needs the magnetic field to be applied along a different crystallographic direction from the one for skyrmion creation.…”

Magnetic Skyrmions with Unconventional Helicity Polarization in a Van Der Waals Ferromagnet

“…Moreover, room‐temperature skyrmion lattice has recently been observed in Co‐doped Fe 5 GeTe 2 . [ 84 ] The doping of Co atoms changes the crystal structure to the P 6 3 mc space group, resulting in the DMI and Néel‐type skyrmions. Another recent study reported a record high T c of 478 K in Ni‐doped Fe 5 GeTe 2 .…”

Integrated Memory Devices Based on 2D Materials

“…[ 171 ] In addition, its broken inversion symmetry gives rise to Néel‐type skyrmions. [ 172 ] Considering the successful large‐scale epitaxial growth of Fe 3 GeTe 2 and Fe 5 GeTe 2 , [ 177,178 ] wafer‐sized (Fe 0.5 Co 0.5 ) 5− x GeTe 2 may be achieved using a similar approach because of the similarity in their in‐plane lattice parameters.…”

“…Recently, Zhang et al [ 171 ] reported a 2D polar ferromagnet, (Fe 0.5 Co 0.5 ) 5− x GeTe 2 , with a Curie temperature of ≈350 K. Notably, Néel‐type skyrmions were observed in this material at room temperature. [ 172 ] The findings on room‐temperature skyrmions in 2D magnets pave the way for skyrmion‐based 2D IMDs. Although related research remains in its infancy, the great potential of magnetic skyrmions opens an interesting perspective for future exploration of emerging memories based on 2D magnets.…”

“…[102] However, downscaling of skyrmion-based IMDs seems to be more challenging. On one hand, the skyrmion size in 2D ferromagnets is typically on the order of hundreds of nanometers, [163,165,172] making them uncompetitive with conventional magnetic multilayers or bulk materials for size scaling. [191] On the other hand, the formation of skyrmions is a result of the competition among various magnetic interactions, including magnetic anisotropy and the dipolar interaction.…”