2009/09/30 by A. V. Kalinov, O. Yu. Gorbenko, Alexander N. Taldenkov +15
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Condensed matter physics #Ferromagnetism #Magnetic and transport properties of perovskites and related materials #Magnetic field #Magnetization #Materials science #Paramagnetism #Phase (matter) #Phase diagram #Phase transition #Physics #Physics of Superconductivity and Magnetism #Spin (aerodynamics) #Spin states #Thermodynamics #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.81.134427
13 pages, including 11 figures, to be published in Phys. Rev. B
arxiv created 2010/04/06 · openalex publication_date 2010/04/21 · arxiv updated 2015/05/14 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present the study of magnetization, thermal expansion, specific heat, resistivity, and ac susceptibility of (Pr_1\ensuremath-yEuy)0.7Ca0.3CoO3 cobaltites. The measurements were performed on ceramic samples with y=0.12--0.26 and y=1. Based on these results, we construct the phase diagram, including magnetic and spin-state transitions. The transition from the low-to-intermediate spin state is observed for the samples with y>0.18, whereas for a lower Eu-doping level, there are no spin-state transitions, but a crossover between the ferromagnetic and paramagnetic states occurs. The effect of oxygen isotope substitution along with Eu doping on the magnetic/spin state is discussed. The oxygen-isotope substitution (16O by 18O) is found to shift both the magnetic and spin-state phase boundaries to lower Eu concentrations. The isotope effect on the spin-state transition temperature (y>0.18) is rather strong but it is much weaker for the transition to a ferromagnetic state (y<0.18). The ferromagnetic ordering in the low-Eu-doped samples is shown to be promoted by the Co4+ ions, which favor the formation of the intermediate-spin state of neighboring Co3+ ions.