Michael A. Korotin | Searcharxiv

arXiv2016

Magnetic properties of Fe$_{1-x}$Ni$_x$ alloy from CPA+DMFT perspectives

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 behavior and extracted effective temperatures are in agreement with the experimental results. The individual squared magnetic moments obtained as function of nickel concentration follow the same trends as experimental data. An analysis of the ionic and spin weights shows a possibility of a high-spin to intermediate- and low-spin states transitions at high temperatures.

cond-mat.str-el↗

arXiv2001

Coulomb correlation and magnetic ordering in double-layered manganites: LaSr$_2$Mn$_2$O$_7$

A detailed study of the electronic structure and magnetic configurations of the 50 % hole-doped double layered manganite LaSr$_2$Mn$_2$O$_7$ is presented. We demonstrate that the on-site Coulomb correlation (U) of Mn d electrons {\it (i)} significantly modifies the electronic structure, magnetic ordering (from FM to AFM), and interlayer exchange interactions, and {\it (ii)} promotes strong anisotropy in electrical transport, reducing the effective hopping parameter along the {\it c} axis for electrically active $e_g$ electrons. This findng is consistent with observations of anisotropic transport -- a property which sets this manganite apart from conventional 3D systems. A half-metallic band structure is predicted with both the LSDA and LSDA+U methods. The experimentally observed A-type AFM ordering in LaSr$_2$Mn$_2$O$_7$ is found to be energetically more favorable with U $\geq$ 7 eV. A simple interpretation of interlayer exchange coupling is given within double and super-exchange mechanisms based on the dependencies on U of the effective exchange parameters and $e_g$ state sub-band widths.

cond-mat.str-el↗