Strongly inhomogeneous conduction in cobaltite films: Non-Gaussian resistance noise

Vladimir Orlyanchik, M. B. Weissman, Maria A. Torija, M. Sharma, C. Leighton

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

Strongly non-Gaussian conductance fluctuations are found in relatively large (e.g., 1× 10-10 cm3) samples of (001)-oriented ∼50-nm -thick epitaxial films of the nominally ferromagnetic and metallic perovskite cobaltite La0.5Sr0.5CoO3. Field dependences of Boltzmann factors of individual fluctuators show them to be magnetic regions with of order 1× 104 Bohr magnetons. Given the size of the fluctuating regions, the size of the discrete conductance fluctuations would be anomalously large unless the conductance were strongly inhomogeneous as expected for magnetoelectronic phase-separation effects known to occur in some bulk cobaltites at lower concentrations or with polycrystalline structure. Temperature dependences of Boltzmann factors indicate small energy and entropy changes, more like magnetic rotations than like fluctuations between phases. The films, like bulk samples of the same composition, show resistance increasing with temperature in Van der Pauw measurements; but resistance in strip-shaped regions weakly decreases with temperature, indicating particularly extreme effects of the inhomogeneous magnetic orientation dependent conductivity.

Original languageEnglish (US)
Article number094430
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume78
Issue number9
DOIs
StatePublished - Sep 30 2008

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conduction
Magnetoelectronics
Epitaxial films
Thick films
Phase separation
Perovskite
Temperature
Bohr magneton
Entropy
thick films
low concentrations
strip
Chemical analysis
cobaltite
entropy
conductivity
temperature dependence
temperature
energy
perovskite

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Strongly inhomogeneous conduction in cobaltite films : Non-Gaussian resistance noise. / Orlyanchik, Vladimir; Weissman, M. B.; Torija, Maria A.; Sharma, M.; Leighton, C.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 78, No. 9, 094430, 30.09.2008.

Research output: Contribution to journalArticle

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