X-ray absorption and x-ray magnetic dichroism study on Ca(3)CoRhO(6) and Ca(3)FeRhO(6)

Physical review. B, Condensed matter (Impact Factor: 3.66). 04/2008; 77. DOI: 10.1103/PhysRevB.77.205111
Source: arXiv


By using x-ray absorption spectroscopy at the Rh L(2,3), Co L(2,3), and Fe L(2,3) edges, we find a valence state of Co(2+)/Rh(4+) in Ca(3)CoRhO(6) and of Fe(3+)/Rh(3+) in Ca(3)FeRhO(6). X-ray magnetic circular dichroism spectroscopy at the Co L(2,3) edge of Ca(3)CoRhO(6) reveals a giant orbital moment of about 1.7 mu(B), which can be attributed to the occupation of the minority-spin d(0)d(2) orbital state of the high-spin Co(2+) (3d(7)) ions in trigonal prismatic coordination. This active role of the spin-orbit coupling explains the strong magnetocrystalline anisotropy and Ising-type magnetism of Ca(3)CoRhO(6).

Download full-text


Available from: Zhiwei Hu
  • [Show abstract] [Hide abstract]
    ABSTRACT: The homogeneity range of the CaCo{sub 2-v}Mn{sub v}O solid-solution phase covers the entire composition interval from v=0 to 1. A systematic powder X-ray and neutron diffraction, magnetic susceptibility, and magnetization study has been carried out to investigate effects of the Mn-for-Co substitution on structural and magnetic properties. The Mn substitution concerns primarily only the octahedral Co1 site of the CaCo1Co2O crystal structure, whereas the trigonal-prismatic Co2 site structurally is left essentially unaffected. The CaCo{sub 2-v}Mn{sub v}O crystal structure belongs to space group R3-barc with unit-cell dimensions (in hexagonal setting) 9.084{
    No preview · Article · Feb 2009 · Journal of Solid State Chemistry
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a combined experimental and theoretical x-ray absorption spectroscopy study of the class of cobaltates YBaCo4O7 and YBaCo3MO7 (M=Al, Fe). The focus is on the local electronic and magnetic properties of the transition metal ions in these geometrically frustrated kagomé compounds. For the mixed valence cobaltate YBaCo4O7, both the Co2+ and Co3+ are found to be in the high-spin state. The stability of these high-spin states in tetrahedral coordination is compared with those in the more studied case of octahedral coordination. For the compound YBaCo3FeO7, we find exclusively Co2+ and Fe3+ as charge states.
    Full-text · Article · Aug 2009 · Physical review. B, Condensed matter
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We have investigated the magnetic behavior of nano crystals, synthesized by high-energy ball-milling, for a well-known geometrically frustrated spin-chain system, Ca3CoRhO6, and compared its magnetic characteristics with those of the bulk form by measuring ac and dc magnetization. The features attributable to the onset of ‘partially disordered antiferromagnetism’ (characterizing the bulk form) are not seen in the magnetization data of the nano particles; the magnetic moment at high fields in the very low temperature range in the magnetically ordered state gets relatively enhanced in the nano particles. It appears that the ferromagnetic intrachain interaction, judged by the sign of the paramagnetic Curie temperature, is preserved in the nano particles. These trends are opposite to those seen in the nano particles of Ca3Co2O6. However, the complex spin-dynamics as evidenced by large frequency dependence of ac susceptibility is retained in the nano particles as well. Thus, there are some similarities and dissimilarities between the properties of the nano particles and those of the bulk. We believe that these findings will be useful to understand correlation lengths deciding various properties of geometrical frustration and/or spin-chain phenomena.
    Full-text · Article · Oct 2009 · Solid State Communications
Show more