Spin state and magnetic ordering of half-doped Nd0.5Sr0.5CoO3 cobaltite

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:422

Article

Reis, M. S.¹  Rocco, D. L.^1,2  Caraballo Vivas, R. J.¹  Pimentel, B.¹  Checca, N. R.¹  Torrao, R.¹  Paixao, L.^1,3  dos Santos, A. M.³ 

[1] Univ Fed Fluminense, Inst Fis, BR-24210340 Niteroi, RJ, Brazil

[2] Ctr Fed Educ Tecnol Minas Gerais CEFET MG, Dept Formacao Geral, Campus Timoteo, BR-35180008 Belo Horizonte, MG, Brazil

[3] Oak Ridge Natl Lab, Quantum Condensed Matter Div, Oak Ridge, TN 37831 USA

关键词: Cobaltites;    Magnetic phase diagram;    Anomalous XRD;    Syncrotron;    Magnetic entropy change;    Magnetocaloric effect;   

DOI  :  10.1016/j.jmmm.2016.08.080

来源: Elsevier

【 摘 要 】

Cobaltites show intriguing magnetic and transport properties, when compared with manganites for instance, as they exhibit an additional degree of freedom: the spin state of the Co ions. For Nd0.5Sr0.5CoO3 this spin configuration is not well-established, as well as the magnetic ordering below the Curie temperature. Thus, in the present effort, magnetization measurements and a mean-field theoretical model were developed in order to understand in detail these aspects of the half-doped Nd0.5Sr0.5CoO3 cobaltite. These results show that the Co and Nd magnetic sub-lattices couple antiferromagnetically below Curie temperature T-c=215 K down to very low temperature. These findings clarify the presence of the plateau observed at 80 K on M(T) curve, which is erroneously attributed, in the literature, to the onset of an antiferromagnetic ordering. Magnetization data also clearly shows that Co3+ and Ed(4+) are in an intermediate spin state. In addition, experimental and theoretical magnetic entropy changes were determined and a comparative analysis among these two leads to ratify the results above claimed. Finally, from all those results, a magnetic phase diagram for Nd0.5Sr0.5CoO3. could be drawn. (C) 2016 Elsevier B.V. All rights reserved.

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