Electronic structure of Fe and magnetism in the $3d/5d$ double perovskites Ca$_2$FeReO$_6$ and Ba$_2$FeReO$_6$

E. Granado; J. C. Cezar; C. Azimonte; J. Gopalakrishnan; K. Ramesha

doi:10.1103/PhysRevB.99.195118

paper

Electronic structure of Fe and magnetism in the $3 d /5 d$ double perovskites Ca $_{2}$ FeReO $_{6}$ and Ba $_{2}$ FeReO $_{6}$

arXiv:1905.04988 · doi:10.1103/PhysRevB.99.195118

Abstract

The Fe electronic structure and magnetism in (i) monoclinic Ca $_{2}$ FeReO $_{6}$ with a metal-insulator transition at $T_{M I} \sim 140$ K and (ii) quasi-cubic half-metallic Ba $_{2}$ FeReO $_{6}$ ceramic double perovskites are probed by soft x-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD). These materials show distinct Fe $L_{2, 3}$ XAS and XMCD spectra, which are primarily associated with their different average Fe oxidation states (close to Fe $^{3 +}$ for Ca $_{2}$ FeReO $_{6}$ and intermediate between Fe $^{2 +}$ and Fe $^{3 +}$ for Ba $_{2}$ FeReO $_{6}$ ) despite being related by an isoelectronic (Ca $^{2 +}$ /Ba $^{2 +}$ ) substitution. For Ca $_{2}$ FeReO $_{6}$ , the powder-averaged Fe spin moment along the field direction ( $B = 5$ T), as probed by the XMCD experiment, is strongly reduced in comparison with the spontaneous Fe moment previously obtained by neutron diffraction, consistent with a scenario where the magnetic moments are constrained to remain within an easy plane. For $B = 1$ T, the unsaturated XMCD signal is reduced below $T_{M I}$ consistent with a magnetic transition to an easy-axis state that further reduces the powder-averaged magnetization in the field direction. For Ba $_{2}$ FeReO $_{6}$ , the field-aligned Fe spins are larger than for Ca $_{2}$ FeReO $_{6}$ ( $B = 5$ T) and the temperature dependence of the Fe magnetic moment is consistent with the magnetic ordering transition at $T_{C}^{B a} = 305$ K. Our results illustrate the dramatic influence of the specific spin-orbital configuration of Re $5 d$ electrons on the Fe $3 d$ local magnetism of these Fe/Re double perovskites.

7 pages, 3 figures

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Magnetic excitations in double perovskite iridates La $_{2}$ $M$ IrO $_{6}$ ( $M$ = Co, Ni, and Zn) mediated by 3 $d$ -5 $d$ hybridization

Electronic structure of Fe and magnetism in the 3d/5d double perovskites Ca2​FeReO6​ and Ba2​FeReO6​

Abstract

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Cited by in corpus (1)

Electronic structure of Fe and magnetism in the $3 d /5 d$ double perovskites Ca $_{2}$ FeReO $_{6}$ and Ba $_{2}$ FeReO $_{6}$