Transition Metal-Nonmetal in Conductivity of Ceramic Hole-Doped Cobaltites

Yurii Nikolaevich Chiang, Mihail Olegovich Dzyuba, Olga Georgievna Shevchenko, Anatolii Antonovich Kozlovskii, Vitalii Philipovich Khirnyi

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DOI: 10.4236/jmp.2010.15045                

Abstract

In bulk granulated cobaltite La1–xSrxCoO3 with the size of granules of order of 1 micron at strontium hole doping with replacement factor x = 0.35, a transition “metal-nonmetal” in the conductivity was revealed, presumably connected with AFM ordering of the moments of granules. The assumption is proved by the agreement between the experiment and results of calculation within the limits of a model offered for electron transport based on the account of in-granule double exchange Zener mechanism and intergranule mechanism of spin-polarized tunneling on the nearest neighbours with AFM exchange interaction. The calculation differs in that conductivities within granules are summarized, while total resistance of the system is represented as a sum of resistances of the granules. In addition, the existence of AFM interaction between granules is supported by the observed insensitivity of conductivity to a low external magnetic field (up to 5 kOe).

Keywords

Granulated Cobaltite, Double Exchange, Spin-Polarised Tunneling

Conflicts of Interest

The authors declare no conflicts of interest.

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