Magnetic and electronic Co states in layered cobaltate GdBaCo2O5.5-x

Abstract

We have performed non-resonant x-ray diffraction, resonant soft and hard x-ray magnetic diffraction, soft x-ray absorption and x-ray magnetic circular dichroism measurements to clarify the electronic and magnetic states of the Co3+ ions in GdBaCo2O5.5. Our data are consistent with a 3+ Py Co HS state at the pyramidal sites and a 3+ Oc Co LS state at the octahedral sites. The structural distortion, with a doubling of the a axis (2ap x 2ap x 2ap cell), shows alternating elongations and contractions of the pyramids and indicates that the metal-insulator transition is associated with orbital order in the t2g orbitals of the 3+ Py Co HS state. This distortion corresponds to an alternating ordering of xz and yz orbitals along the a and c axes for the 3+ Py Co . The orbital ordering and pyramidal distortion lead to deformation of the octahedra, but the 3+ Oc Co LS state does not allow an orbital order to occur for the 3+ Oc Co ions. The soft x-ray magnetic diffraction results indicate that the magnetic moments are aligned in the ab plane but are not parallel to the crystallographic a or b axes. The orbital order and the doubling of the magnetic unit cell along the c axis support a non-collinear magnetic structure. The x-ray magnetic circular dichroism data indicate that there is a large orbital magnetic contribution to the total ordered Co moment.

References in corpus (11)

• The spin state transition in LaCoO${}_3$; revising a revision
• Transport and magnetic properties of GdBaCo_{2}O_{5+x} single crystals: A cobalt oxide with square-lattice CoO_2 planes over a wide range of electron and hole doping
• Spin-state transition in LaCoO3: direct neutron spectroscopic evidence of excited magnetic states
• Selective Spin-State Switch and Metal-Insulator Transition in \boldmath $\mathrm{GdBaC}{\mathrm{o}}_2{\mathrm{O}}_{5.5}$
• A different look at the spin state of Co${}^{3+}$ ions in CoO${}_5$ pyramidal coordination
• Role of magnetic and orbital ordering at the metal-insulator transition in NdNiO3
• Spin structure and magnetic phase transitions in TbBaCo2O5.5
• X-ray Diffraction Study of Superstructure in GdBaCo2O5.5
• Direct observation of oxygen superstructures in manganites
• Existence of the Co3+ Low Spin State in TbBaCo2O5.5
• X-ray and neutron diffraction studies of coupled structural phase transitions in DyBaCo${}_2$O${}_{5.5}$

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• Resonant x-ray scattering in 3d-transition-metal oxides: Anisotropy and charge orderings
• Photo-induced Antiferromagnetic-ferromagnetic Transition and Electronic Structure Modulation in GdBaCo${}_2$O${}_{5.5}$ Thin Film