DFT+DMFT study of the magnetic susceptibility and the correlated electronic structure in transition-metal intercalated NbS2_2

The Co-intercalated NbS$_2$ (Co$_{1/3}$NbS$_2$) compound exhibits large anomalous Hall conductance, likely due to the non-coplanar magnetic ordering of Co spins. In this work, we study the relation between this novel magnetism and the correlated electronic structure of Co$_{1/3}$NbS$_2$ by adopting dynamical mean field theory (DMFT) to treat the correlation effect of Co $d$ orbitals. We find that the hole doping of Co$_{1/3}$NbS$_2$ can tune the size of the Nb hole pocket at the DMFT Fermi surface, producing features consistent with those observed in angle resolved photoemission spectra [Phys. Rev. B 105, L121102 (2022)]. We also compute the momentum-resolved spin susceptibility, and correlate it with the Fermi surface shape. We find that the magnetic ordering wavevector of Co$_{1/3}$NbS$_2$ obtained from the peak in spin susceptibility agrees with the one observed experimentally by neutron scattering; it is compatible with commensurate non-coplanar $3q$ spin structure. We also discuss how results change if some other than Co transition metal intercalations are used.Comment: 11 pages, 11 figure

The magnetic excitation spectra in BaFe2_{2}As2_{2}: a two-particle approach within DFT+DMFT

We study the magnetic excitation spectra in the paramagnetic state of BaFe$_{2}$As$_{2}$ from the \textit{ab initio} perspective. The one-particle excitation spectrum is determined within the combination of the density functional theory and the dynamical mean-field theory method. The two-particle response function is extracted from the local two-particle vertex function, also computed by the dynamical mean field theory, and the polarization function. This method reproduces all the experimentally observed features in inelastic neutron scattering (INS), and relates them to both the one particle excitations and the collective modes. The magnetic excitation dispersion is well accounted for by our theoretical calculation in the paramagnetic state without any broken symmetry, hence nematic order is not needed to explain the INS experimental data.Comment: 5 pages, 5 figure