3 research outputs found
Skyrmions and magnetic bubbles in spin-orbit coupled metallic magnets
Motivated by the observation of Skyrmion-like magnetic textures in 2D
itinerant ferromagnets FeGeTe (), we develop a microscopic
model combining itinerant magnetism and spin-orbit coupling on a triangular
lattice. The ground state of the model in the absence of magnetic field
consists of filamentary magnetic domain walls revealing a striking similarity
with our magnetic force microscopy experiments on FeGeTe. In the
presence of magnetic field, these filaments were found to break into large size
magnetic bubbles in our experiments. We identify uniaxial magnetic anisotropy
as an important parameter in the model that interpolates between magnetic
Skyrmions and ferromagnetic bubbles. Consequently, our work uncovers new
topological magnetic textures that merge properties of Skyrmions and
ferromagnetic bubbles
High transport spin polarization in the van der Waals ferromagnet FeGeTe
The challenging task of scaling-down the size of the power saving electronic
devices can be accomplished by exploiting the spin degree of freedom of the
conduction electrons in van der Waals (vdW) spintronic architectures built with
2D materials. One of the key components of such a device is a near-room
temperature 2D ferromagnet with good metallicity that can generate a highly
spin-polarized electronic transport current. However, most of the known 2D
ferromagnets have either a very low temperature ordering, poor conductivity, or
low spin polarization. In this context, the FeGeTe (with )
family of ferromagnets stand out due to their near-room temperature
ferromagnetism and good metallicity. We have performed spin-resolved Andreev
reflection spectroscopy on FeGeTe ( 273 K) and
demonstrated that the ferromagnet is capable of generating a very high
transport spin polarization, exceeding 50. This makes FeGeTe a
strong candidate for application in all-vdW power-saving spintronic devices.Comment: Accepted for publication in Physical Review
Porous covalent organic nanotubes and their assembly in loops and toroids
Carbon nanotubes, and synthetic organic nanotubes more generally, have in recent decades been widely explored for application in electronic devices, energy storage, catalysis and biosensors. Despite noteworthy progress made in the synthesis of nanotubular architectures with well-defined lengths and diameters, purely covalently bonded organic nanotubes have remained somewhat challenging to prepare. Here we report the synthesis of covalently bonded porous organic nanotubes (CONTs) by Schiff base reaction between a tetratopic amine-functionalized triptycene and a linear dialdehyde. The spatial orientation of the functional groups promotes the growth of the framework in one dimension, and the strong covalent bonds between carbon, nitrogen and oxygen impart the resulting CONTs with high thermal and chemical stability. Upon ultrasonication, the CONTs form intertwined structures that go on to coil and form toroidal superstructures. Computational studies give some insight into the effect of the solvent in this assembly process