Sr doping effects on the transport and magnetic properties of GdBaCo2O5+delta

• Published in: Physica. B, Condensed matter Condensed matter, 2008-03, Vol.403 (4), p.631-635
• Main Authors: Janaki, J, Bharathi, A, Gayathri, N, Yasodha, P, Premila, M, Sastry, V S, Hariharan, Y
• Format: Article
• Language: English
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2007.09.066

Studies on some new members of the cobalt perovskite Gd1-xSrxBaCo2O5+delta with low strontium concentrations (0 < x < 0.1) have been carried out with the aim of investigating possible metallization of the GdBaCo2O5+delta system by hole doping. Low temperature electrical resistivity, magnetic susceptibility and thermopower of the above system have been studied. The pristine compound with x=0 and delta0.5 exhibits a semiconductor-like behavior and two magnetic transitions below room temperature. Upon Sr2+ substitution, there is a fall in resistivity by 2-3 orders of magnitude at low temperature and also a dramatic reduction in the ferromagnetic to antiferromagnetic transition temperature. These changes can be explained on the basis of hole doping (and increase in the Co4+content). Evidence for an increase in Co4+ with Sr2+ substitution is provided by iodometric analysis.