2009/01/23 by C. F. Chang, Z. Hu, Zhiwei Hu +11 · 173 citations
Chemistry · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Charge (physics) #Charge ordering #Chemistry #Condensed matter physics #Crystallography #Ion #Magnetic and transport properties of perovskites and related materials #Materials science #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Spin (aerodynamics) #Thermodynamics #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevlett.102.116401
published in Physical Review Letters 102(11), 116401 (American Physical Society) · 5 pages, 3 figures
arxiv created 2009/01/23 · openalex publication_date 2009/03/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Using Co\mathrm\text\ensuremath-L2,3 and O\mathrm\text\ensuremath-K x-ray absorption spectroscopy, we reveal that the charge ordering in La1.5Sr0.5CoO4 involves high spin (S=3/2) Co2+ and low spin (S=0) Co3+ ions. This provides evidence for the spin-blockade phenomenon as a source for the extremely insulating nature of the La_2\ensuremath-xSrxCoO4 series. The associated eg2 and eg0 orbital occupation accounts for the large contrast in the Co-O bond lengths and, in turn, the high charge ordering temperature. Yet, the low magnetic ordering temperature is naturally explained by the presence of the nonmagnetic (S=0) Co3+ ions. From the identification of the bands we infer that La1.5Sr0.5CoO4 is a narrow band material.