Electronic structure study of double perovskites $A_{2} {FeReO}_{6} (A = B a, S r, C a)$ and ${Sr}_{2} M {MoO}_{6}$ $(M = C r, M n, F e, C o)$ by LSDA and $LSDA + U$

We have implemented a systematic LSDA and

LSDA + U

study of the double perovskites

A_{2} {FeReO}_{6}

(A = B a, S r, C a)

and Sr

_{2} M

MoO

_{6}

(M = C r, M n, F e, C o)

for understanding of their intriguing electronic and magnetic properties. The results suggest a ferrimagnetic (FiM) and half-metallic (HM) state of

A_{2} {FeReO}_{6}

(A = B a, S r)

due to a

pdd - π

coupling between the down-spin

{Re}^{5 +} / {Fe}^{3 +}

t_{2 g}

orbitals via the intermediate

O {2 p}_{π}

ones, also a very similar FiM and HM state of

{Sr}_{2} {FeMoO}_{6} .

In contrast, a decreasing Fe

t_{2 g}

component at Fermi level

{(E}_{F})

in the distorted

{Ca}_{2} {FeReO}_{6}

partly accounts for its nonmetallic behavior, while a finite

pdd - σ

coupling between the down-spin

{Re}^{5 +} / {Fe}^{3 +} e_{g}

orbitals being present at

E_{F}

serves to stabilize its FiM state. For

{Sr}_{2} {CrMoO}_{6}

compared with

{Sr}_{2} {FeMoO}_{6},

the coupling between the down-spin

{Mo}^{5 +} / {Cr}^{3 +}

t_{2 g}

orbitals decreases as a noticeable shift up of the

{Cr}^{3 +} 3 d

levels, which is likely responsible for the...

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Electronic structure study of double perovskites A2FeReO6(A=Ba,Sr,Ca) and Sr2MMoO6 (M=Cr,Mn,Fe,Co) by LSDA and LSDA+U