Antiferromagnet–ferromagnet transition in the cobaltites

Магнетизм

Автор(и)

  • I.O. Troyanchuk Scientific-Practical Materials Research Centre of NAS of Belarus, 19 P. Brovka Str., Minsk 220072, Belarus
  • M.V. Bushinsky Scientific-Practical Materials Research Centre of NAS of Belarus, 19 P. Brovka Str., Minsk 220072, Belarus
  • D.V. Karpinsky Scientific-Practical Materials Research Centre of NAS of Belarus, 19 P. Brovka Str., Minsk 220072, Belarus
  • V.A. Sirenko B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, 47 Lenin Ave., Kharkov 61103, Ukraine

DOI:

https://doi.org/10.1063/1.4736615

Ключові слова:

antiferromagnet, oxygen vacancies, spin state transition, layered perovskite.

Анотація

The three series oxygen-deficient cobaltites La0.5Ba0.5CoO3–δ, LnBaCo2O5.5 and Sr2YCo4O10.5 have been studied. It has been shown that La0.5Ba0.5CoO3 is an insulating ferromagnet whereas La0.5Ba0.5CoO2.75 is a pure antiferromagnet in which the oxygen vacancies are disordered. The oxygen-vacancies ordering leads to appearance of the ferromagnetic component apparently due to a formation of the noncollinear magnetic structure. The antiferromagnet–“ferromagnet” transition is accompanied by a giant magnetoresistance. It is suggested that in the ferromagnetic oxidized compounds Co3+ and Co4+ ions adopt intermediate spin state whereas for antiferromagnetic (Co4+-free) compositions Co3+ ions have high-spin state (pyramids CoO5) and dominant low-spin state (octahedra CoO6). In both ferromagnetic and antiferromagnetic compounds the superexchange via oxygen plays an essential role in a formation of the magnetic properties.

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Опубліковано

2012-05-17

Як цитувати

(1)
Troyanchuk, I.; Bushinsky, M.; Karpinsky, D.; Sirenko, V. Antiferromagnet–ferromagnet Transition in the Cobaltites: Магнетизм. Fiz. Nizk. Temp. 2012, 38, 833-841.

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