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Magnetic properties of a $sigma-$Fe$_{16}$Cr$_{14}$ alloy calculated with the charge and spin self- consistent Korringa-Kohn-Rostoker (KKR) and combined with coherent potential approximation (KKR-CPA) methods are reported. Non-magnetic state as well as various magnetic orderings were considered, i.e. ferromagnetic (FM) and more complex anti-parallel (called APM) arrangements for selected sublattices, as follows from the symmetry analysis. It has been shown that the Stoner criterion applied to non-magnetic density of states at the Fermi energy, $E_F$ is satisfied for Fe atoms situated on all five lattice sites, while it is not fulfilled for all Cr atoms. In FM and APM states, the values of magnetic moments on Fe atoms occupying various sites are dispersed between 0 and 2.5 $mu_B$, and they are proportional to the number of Fe atoms in the nearest-neighbor shell. Magnetic moments of Cr atoms havin much smaller values were found to be coupled antiparallel to those of Fe atoms. The average value of the magnetic moment per atom was found to be $<mu>=0.55 mu_B$ that is by a factor of 4 larger than the experimental value found for a $sigma-$Fe$_{0.538}$Cr$_{0.462}$ sample. Conversely, admitting an anti- parallel ordering (APM model) on atoms situated on C and D sites, according to the group theory and symmetry analysis results, yielded a substantial reduction of $<mu>$ to 0.20 $mu_B$. Further diminution of $<mu>$ to 0.15 $mu_B$, which is very close to the experimental value of 0.14 $mu_B$, has been achieved with the KKR-CPA calculations by considering a chemical disorder on sites B, C and D.
The electronic, magnetic and transport properties of Fe intercalated 2H-TaS$_2$ have been investigated by means of the Korringa-Kohn-Rostoker (KKR) method. The non-stoichiometry and disorder in the system has been accounted for using the Coherent Pot
Formation energy of the $sigma$-phase in the Fe-Cr alloy system, $Delta E$, was computed versus the occupancy changes on each of the five possible lattice sites. Its dependence on a number of Fe-atoms per unit cell, $N_{Fe}$, was either monotonically
Experimental investigation as well as theoretical calculations, of the Fe-partial phonon density-of-states (DOS) for nominally Fe_52.5Cr_47.5 alloy having (a) alpha- and (b) sigma-phase structure were carried out. The former at sector 3-ID of the Adv
We use a combination of the coherent potential approximation and dynamical mean field theory to study magnetic properties of the Fe$_{1-x}$Ni$_x$ alloy from a first principles. Calculated uniform magnetic susceptibilities have a Curie-Weiss-like beha
We present spin wave dispersions in MnO, NiO, and $alpha$-MnAs based on the quasiparticle self-consistent $GW$ method (qsgw), which determines an optimum quasiparticle picture. For MnO and NiO, qsgw results are in rather good agreement with experimen