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Hybridized orbital states in spin-orbit coupled 3 d − 5 d double perovskites studied by x-ray absorption spectroscopy

2018; American Physical Society; Volume: 97; Issue: 12 Linguagem: Inglês

10.1103/physrevb.97.125123

2469-9977

Min‐Cheol Lee, Sanghyun Lee, Choongjae Won, K. D. Lee, N. Hur, Jeng‐Lung Chen, Deok‐Yong Cho, Tae Won Noh,

Multiferroics and related materials

We investigated the orbital hybridization mechanism in $3d\ensuremath{-}5d$ double perovskites (DPs) of ${\mathrm{La}}_{2}{\mathrm{CoIrO}}_{6}$ and ${\mathrm{La}}_{2}{\mathrm{CoPtO}}_{6}$ using x-ray absorption spectroscopy. It is clearly evidenced by O $K$-edge and Co $K$-edge x-ray absorption spectra that the Co $3d$ orbitals hybridize not only with the half-filled Ir/Pt ${j}_{\mathrm{eff}}$ states but also with the fully empty (unpolarized) Ir/Pt ${e}_{g}$ states in both DPs. The Co $3d$ ${e}_{g}$-Ir $5d$ ${e}_{g}$ hybridization cannot contribute to the ferrimagnetic long-range order in ${\mathrm{La}}_{2}{\mathrm{CoIrO}}_{6}$ established by spin-selective Co $3d$ ${t}_{2g}$-Ir $5d$ ${j}_{\mathrm{eff}}$ hybridization through the intermediate oxygen $p$ state but could serve as an origin of paramagnetism. The strengths of such orbital hybridizations were found to be almost invariant to temperature, even far above the Curie temperature, implying persistent paramagnetism against the antiferromagnetic ordering in the spin-orbit entangled $3d\ensuremath{-}5d$ DPs.