Effect of copper doping on charge ordering in La1/3Ca2/3Mn1 ? y Cu y O3 (0 ≤ y ≤ 0.07) |
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Authors: | T S Orlova J Y Laval Ph Monod V S Zakhvalinski? V M Egorov and Yu P Stepanov |
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Institution: | (1) Ioffe Physicotechnical Institute, Russian Academy of Sciences, Politekhnicheskaya ul. 26, St. Petersburg, 194021, Russia;(2) Laboratoire de Physique du Solide, CNRS ESPCI, Paris, 75231, France;(3) Belgorod State University, ul. Pobedy 85, Belgorod, 308015, Russia |
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Abstract: | The effect of copper doping on charge-orbital ordering in La1/3Ca2/3Mn1 − y
Cu
y
O3 (0 ≤ y ≤ 0.07) is studied by measuring the temperature dependences of the magnetization, the electrical resistivity, and the heat
capacity in combination with an electron microscopic investigation of the structure. It is demonstrated that copper doping
leads to a lowering of the charge ordering temperature T
CO and that this decrease is proportional to the decrease in the Mn3+ ion concentration. In the temperature range 5–300 K, the semiconducting pattern of the electrical resistivity persists for
all values of 0 ≤ y ≤ 0.07. Electron microscope studies have shown that the presence of copper suppresses the formation of a regular superstructure,
which is characteristic of the undoped starting compound, beginning already from low concentrations (y = 0.01). Differential scanning calorimetry revealed a substantial decrease in the transition entropy at the onset of charge
ordering in copper-doped samples as compared to the starting compound. Doping with copper destroys long-range charge-orbital
ordering and retains apparently only short-range order.
Original Russian Text ? T.S. Orlova, J.Y. Laval, Ph. Monod, V.S. Zakhvalinskiĭ, V.M. Egorov, Yu.P. Stepanov, 2009, published
in Fizika Tverdogo Tela, 2009, Vol. 51, No. 1, pp. 91–97. |
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Keywords: | |
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