2004/05/31 by J. Baier, S. Jodlauk, M. Kriener +6 · 1 citation
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Magnetic and transport properties of perovskites and related materials #Rare-earth and actinide compounds #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.71.014443
published as Phys. Rev. B 71, 014443 (2005) · 10 pages, 6 figures
openalex publication_date 2005/01/31 · arxiv created 2005/02/10 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We present a study of the structure, the electric resistivity, the magnetic susceptibility, and the thermal expansion of La_1\ensuremath-xEuxCoO3. LaCoO3 shows a temperature-induced spin-state transition around 100\phantom\rule0.3em0exK and a metal-insulator transition around 500\phantom\rule0.3em0exK. Partial substitution of La3+ by the smaller Eu3+ causes chemical pressure and leads to a drastic increase of the spin gap from about 190\phantom\rule0.3em0exK in LaCoO3 to about 2000\phantom\rule0.3em0exK in EuCoO3, so that the spin-state transition is shifted to much higher temperatures. A combined analysis of thermal expansion and susceptibility gives evidence that the spin-state transition has to be attributed to a population of an intermediate-spin state without orbital degeneracy for x<0.5 and with orbital degeneracy for larger x. In contrast to the spin-state transition, the metal-insulator transition is shifted only moderately to higher temperatures with increasing Eu content, showing that the metal-insulator transition occurs independently from the spin-state distribution of the Co3+ ions. Around the metal-insulator transition the magnetic susceptibility shows a similar increase for all x and approaches a doping-independent value around 1000\phantom\rule0.3em0exK, indicating that well above the metal-insulator transition the same spin state is approached for all x.