Comparative studies of magnetic properties in osmates with the double perovskite structure

This is the authors' abstract. We don't add key points for this paper.

Using the first-principles density functional approach, we comparatively studied the electronic and magnetic properties of two series of ordered double perovskite, Ba₂BOsO₆4pt0ex(B=Sc,Y,4pt0exand In) and A₂ScOsO₆4pt0ex(A=Ba,Sr,4pt0exand Ca). The electronic structure calculations indicate that the Os ion bears the nominal t2g³ state with oxidation state $5+$ and is the only magnetically active one in all compounds. In nice agreement with the experimental observations, all of them stabilized in the type I antiferromagnetic alignment, which is mediated by the moderate nearest-neighbor antiferromagnetic interactions through the Os-O-B-O-Os90^∘{} route and accompanied by mild next-nearest-neighbor antiferromagnetic coupling via the Os-O-B-O-Os180^∘{} route, in spite of the geometric frustration. The mechanism of the antiferromagnetic interaction has been proposed based on the density of states analysis. In addition, the computed magnetic moment on Os ions, ~20.16em0exμB, is remarkably smaller than the ideal spin-only value. In conjunction with the modest spin-orbit coupling effect, strong covalency between the Os-5d and O-2p states reduces the magnetic moments. More importantly, our results demonstrated that the magnitude of the magnetic couplings as well as magnetic transition temperature TN are directly proportional to the reciprocal of the absolute value of energy mismatch between the B-nd and occupied Os-t2g band; in addition, they are also a function of the Sc-O-Os bond angles, i.e., the buckling of the octahedral connectivity. Moreover, comparison of these two series helps to identify the energy mismatch as the efficient factor to adjust the magnetic interactions.