Enhancement of the Curie temperature in NdBaCo2O5.5 by a-site Ca substitution
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Date
2012-08-24
Journal Title
Journal ISSN
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Publisher
Americal Physical Society
Abstract
Layered cobaltites RBaCo2O5.5 (R = rare earth and Y) undergo a sequence of magnetic and electronic transitions between antiferromagnetic/ferrimagnetic/paramagnetic and insulating/paramagnetic metallic states with respective transition temperatures T-N (similar to 230-260 K) < T-C (similar to 250-290 K) < T-MI (similar to 360 K). We have synthesized a Nd1-xCaxBaCo2O5.5 series (0 <= x <= 0.2) of cation-[(Nd,Ca)/Ba]-ordered and oxygen vacancy-ordered materials and investigated them by neutron diffraction, magnetization, and electronic and thermal transport. We observe that upon Ca doping, T-N is decreasing to 0 for x = 0.1 and T-C is increasing and coincides with T-MI for x > 0.12, which weakly changes with Ca substitution from similar to 360 to similar to 340 K. This is the largest enhancement of T-C observed for these cobaltites. Unlike hole doping by adding oxygen, Ca doping does not disrupt the cation and oxygen vacancy orderings up to x = 0.20. © 2012, American Physical Society.
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Keywords
Paramagnetism, Magnetism, Spin glass state, Calcium, Neutron diffraction, Oxygen
Citation
Kolesnik, S., Dabrowski, B., Chmaissem, O., Avci, S., Hodges, J. P., Avdeev, M., & Świerczek, K. (2012). Enhancement of the Curie temperature in NdBaCo2O5.5 by a-site Ca substitution. Physical Review B, 86(6), Article Number 064434. doi:10.1103/PhysRevB.86.064434