Triangular Spin-Orbit-Coupled Lattice with Strong Coulomb Correlations: Sn Atoms on a SiC(0001) Substrate

Abstract

Two-dimensional (2D) atom lattices provide model setups with Coulomb correlations that induce competing ground states. Here, SiC emerges as a wide-gap substrate with reduced screening. We report the first artificial high-Z atom lattice on SiC(0001) by Sn adatoms, based on experimental realization and theoretical modeling. Density-functional theory of our triangular structure model closely reproduces the scanning tunneling microscopy. Photoemission data show a deeply gapped state (∼2 eV gap), and, based on our calculations including dynamic mean-field theory, we argue that this reflects a pronounced Mott-insulating scenario. We also find indications that the system is susceptible to antiferromagnetic superstructures. Such artificial lattices on SiC(0001) thus offer a novel platform for coexisting Coulomb correlations and spin-orbit coupling, with bearing for unusual magnetic phases and proposed topological quantum states of matter.

Uncertainty principle for experimental measurements: Fast versus slow probes

“…As common practice for such cluster simulated spectra we estimated the strength of the core hole spin-orbit coupling (SOC), and the multipole part of the core-valence interaction from atomic Hartree-Fock calculations 64 . For valence and core SOC we use ζ 5 p = 0.40 eV, and ζ 4 d = 0.41 eV; for the multipole moments of the core valence interaction we use the Slater integrals F 1 = 0.46 eV, F 2 = 1.47 eV, and F 3 = 0.42 eV 65 . The monopole part of the core-hole valence interaction is (in combination with the onsite U of Sn) responsible for the relative shift of the three spectra and fixed by the overall width of the spectrum.…”

α -Sn phase on Si(111): Spin texture of a two-dimensional Mott state

“…If spin-orbit coupling is effective, the electronic effects are intimately related to magnetic phases [12]. In addition, the frustration of spin-1/2 systems on 2D triangular lattices favors complex spin textures [13,14] and leads to new quantum phenomena, e.g., for densely packed Pb monolayers on vicinal Si(111) surfaces a spin-orbit density wave was found with Fermi nesting between helical states and antiferromagnetic ordering [15]. In contrast, on flat Si(111) the 2D nesting vectors are incommensurate, thus keeping this system rather immune against charge density wave formation and possibly enabling superconducting behavior [5,16].…”

Nanoskyrmion engineering with sp -electron materials: Sn monolayer on a SiC(0001) surface

“…We now turn to the low-energy Hubbard model taking into account direct exchange, spin-orbit coupling, and non-local Coulomb interactions [15]. The solution of the electronic Hamiltonian within the Hartree-Fock approximation results in the opening of an energy gap of 2 eV, in agreement with experiment [11]. Further, we consider an extended spin model for Sn/SiC (0001): and estimate the corresponding parameters by using superexchange theory.…”