Abstract
Based on density functional theory combined with low-energy models, we explore the magnetic properties of a hybrid atomic-thick two-dimensional (2D) material made of germanene doped with fluorine atoms in a half-fluorinated configuration (Ge2F). The Fluorine atoms are highly electronegative, which induces magnetism and breaks inversion symmetry, triggering thereby a finite and strong Dzyaloshinskii–Moriya interaction (DMI). The magnetic exchange interactions are of antiferromagnetic nature among the first, second and third neighbors, which leads to magnetic frustration. The Néel state is found to be the most stable state, with magnetic moments lying in the surface plane. This results from the out-of-plane component of the DMI vector, which seems to induce an effective in-plane magnetic anisotropy. Upon application of a magnetic field, spin-spirals and antiferromagnetic skyrmions can be stabilized. We conjecture that this can be realized via magnetic exchange fields induced by a magnetic substrate. To complete our characterization, we computed the spin-wave excitations and the resulting spectra, which could be probed via electron energy loss spectroscopy, magneto-Raman spectroscopy or scanning tunneling spectroscopy.
Highlights
The realization of complex spin-textures hinges on the presence of competing magnetic interactions, which are heavily explored in various materials
We study the presence of chiral spin-textures in half uorinated germanene using density functional theory (DFT) combined with low-energy models with spin–orbit coupling in the spirit of the methodology followed by Mazurenko et al.[46]
X JiFj a^þisa^þis[0] i;ss[0] a^is[0] a^is where i(j) and s(s0) are site and spin indices, a+is are the creation operators, and U00, Uij and JFij represent local Coulomb, non-local Coulomb and non-local (i s j) exchange interactions, respectively, and are obtained using the constrained random phase approximation[52] as implemented in the ABINIT code.[53] tij is a hopping matrix-element taking into account the spin–orbit coupling, which is determined using the Wannier parameterization for the three nearest neighbours
Summary
The realization of complex spin-textures hinges on the presence of competing magnetic interactions, which are heavily explored in various materials. Hybrids.[26,27] Other strategies such as applying a bias voltage or strain are used.[28,29,30] Chemical functionalization, impurities, boundaries and defects are other efficient ways employed in 2D sheets to tune their physical properties and induce magnetic order.[29,31,32,33,34,35] In particular, chemisorption using radicals such as oxygen, hydrogen or uorine atoms on the surface of 2D honeycomb structures leads to long-range magnetism.[36,37,38,39,40] Another example consists of Sn monolayer on SiC(0001) surface, where a strong spin–orbit coupling was found on the basis of a generalized Hubbard model. Noting that magnons in 2D structures have been probed with magnetoRaman spectroscopy[49] and scanning tunneling microscopy,[50] we nally explore the spin-wave excitations characterizing the obtained complex spin-textures
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