Electronic structure of Fe and magnetism in the 3d/5d double perovskites Ca2FeReO6 and Ba2FeReO6

Granado, E and Cezar, JC and Azimonte, C and Gopalakrishnan, J and Ramesha, K (2019) Electronic structure of Fe and magnetism in the 3d/5d double perovskites Ca2FeReO6 and Ba2FeReO6. In: PHYSICAL REVIEW B, 99 (19).

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Abstract

The Fe electronic structure and magnetism in (i) monoclinic Ca2FeReO6 with a metal-insulator transition at T-MI similar to 140 K and (ii) quasicubic half-metallic Ba2FeReO6 ceramic double perovskites are probed by soft x-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD). These materials show distinct Fe L-2,L-3 XAS and XMCD spectra, which are primarily associated with their different average Fe oxidation states (close to Fe3+ for Ca2FeReO6 and intermediate between Fe2+ and Fe3+ for Ba2FeReO6) despite being related by an isoelectronic (Ca2+/Ba2+) substitution. For Ca2FeReO6, 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-MI consistent with a magnetic transition to an easy-axis state that further reduces the powder-averaged magnetization in the field direction. For Ba2FeReO6, the field-aligned Fe spins are larger than for Ca2FeReO6 (B = 5 T) and the temperature dependence of the Fe magnetic moment is consistent with the magnetic ordering transition at T-C(Ba) = 305 K. Our results illustrate the dramatic influence of the specific spin-orbital configuration of Re 5d electrons on the Fe 3d local magnetism of these Fe/Re double perovskites.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Publisher:	AMER PHYSICAL SOC
Additional Information:	Copyright for this article belongs to PHYSICAL REVIEW B
Keywords:	RAY CIRCULAR-DICHROISM; A(2)FEREO(6); TRANSITION; SR2FEMOO6; STATE
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	24 May 2019 09:59
Last Modified:	24 May 2019 10:00
URI:	http://eprints.iisc.ac.in/id/eprint/62720

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