Magnetic inhomogeneity effects in DC transport properties and microwave absorption of La0.5Sr0.5CoO3−δ film

Белевцев, Б. И.; Cherpak, N. T.; Chukanova, I. N.; Gubin, A. I.; Krasovitsky, V. B.; Lavrinovich, A. A.

doi:10.1016/s1386-9477(02)01030-5

Cited by 5 publications

(17 citation statements)

References 5 publications

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“…The minimum is most probably connected with a polycrystalline structure of the film. 19 The behavior of (T) is metallic between these extremum points.…”

Section: B Resistivity and Magnetoresistancementioning

confidence: 98%

“…For cobaltites, this effect was seen earlier in La 0.5 Sr 0.5 CoO 3 film. 19 Since the conductivity in mixed-valence cobaltites increases with an enhancement of the FM order, this behavior just reflects the point that the magnetization increases more easily in a magnetic field parallel to the film plane. It is connected mainly with the shape anisotropy of the magnetization.…”

Section: B Resistivity and Magnetoresistancementioning

confidence: 99%

“…In this case the intergrain tunneling can become activated at low enough temperature, which leads to a nonmetallic behavior of (T). 19 It is clear that the magnetical inhomogeneity due to the phase separation can contribute to this effect in the same way as polycrystalline structure. The MR hysteresis is found to be absent above 90 K, but fields H p are significant already at Tϭ78 K (H pʈ ϭ2.5 kOe and H pЌ ϭ2.0 kOe).…”

Section: La 065 Sr 035 Coo 3 Filmmentioning

confidence: 99%

“…It is difficult to imagine that strengthening of the magnetic order in small isolated clusters embedded in a semiconducting matrix can cause this rather strong effect. 19 It should be suggested, therefore, that an applied magnetic field enhances the intercluster tunneling and/or increases the conductivity of intercluster semiconducting regions. It is quite probable that the magnetic field affects somehow the interface regions between the hole-rich clusters and holepoor matrix ͑which are enriched with Co 3ϩ ions in IS state 9 ͒.…”

Section: B Temperature Dependences Of the Transmittance Kerr Effectmentioning

confidence: 99%

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Spin states and phase separation inLa1−xSrxCoO

et al. 2003

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Optical absorption and transverse Kerr effect spectra, resistivity, and magnetoresistance of La 1Ϫx Sr x CoO 3 (xϭ0.15,0.25,0.35) films have been studied. The temperature dependences of the optical and magneto-optical properties of the films exhibit features which can be attributed to the transition of the Co 3ϩ ions from the low-spin state (Sϭ0) to the intermediate-spin state (Sϭ1) and to orbital ordering of the Co 3ϩ ions in the latter state. The evolution of the properties influenced by doping with Sr is interpreted on the basis of the phase separation model.

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“…The minimum is most probably connected with a polycrystalline structure of the film. 19 The behavior of (T) is metallic between these extremum points.…”

Section: B Resistivity and Magnetoresistancementioning

confidence: 98%

Section: B Resistivity and Magnetoresistancementioning

confidence: 99%

Section: La 065 Sr 035 Coo 3 Filmmentioning

confidence: 99%

Section: B Temperature Dependences Of the Transmittance Kerr Effectmentioning

confidence: 99%

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Spin states and phase separation inLa1−xSrxCoO

et al. 2003

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“…Notice that the transition of such a type is observed in bulk samples of granulated cobaltite LSCO, with the size of grain 1 micron and the specified degree of doping by strontium, for the first time. Such transition, for example, was not observed in bulk ceramics of the same cobaltite but with the size of grain  50 micron and with x > 0.35 [13]. It indicates that the effect is not only rather critical to the level of hole doping, which in general is characteristic of conductivity of perovskite compounds based on oxides of transition metals, but also to structural characteristics such as the size and density of distribution of grains.…”

Section: Resultsmentioning

confidence: 96%

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

Chiang¹,

Dzyuba²,

Шевченко³

et al. 2010

JMP

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In bulk granulated cobaltite La 1-x Sr x CoO 3 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).

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Giant radio-frequency magnetoabsorption effect in the cobaltite ceramic La0.5Sr0.5CoO3

Белевцев

Kirichenko

Cherpak

et al. 2003

Journal of Applied Physics

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The DC transport properties of and the radio-frequency (RF) wave absorption (at 1.33 MHz) in a ceramic sample of La0.5Sr0.5CoO 3−δ are measured. The Curie temperature, Tc, of the sample is about 250 K. A giant negative magnetoabsorption effect is found. In the vicinity of Tc, the absolute value of the magnetoabsorption is about 38% in the rather low magnetic field 2.1 kOe. This differs drastically from the measured DC magnetoresistance (MR) δ(H) = [R(0) − R(H)]/R(0) which is a mere 0.26 % near Tc in the same field and increases to about 2.15 % in H = 20 kOe. The phenomenon can be understood taking into account that the magnetoabsorption is determined by influence of magnetic field on the conductivity and the magnetic permeability, while the MR is determined solely by the former. The magnetoabsorption effect can be used to develop RF devices controlled by magnetic field and temperature.

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Magnetic inhomogeneity effects in DC transport properties and microwave absorption of La0.5Sr0.5CoO3−δ film

Cited by 5 publications

References 5 publications

Spin states and phase separation inLa1−xSrxCoO

Spin states and phase separation inLa1−xSrxCoO

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

Giant radio-frequency magnetoabsorption effect in the cobaltite ceramic La0.5Sr0.5CoO3

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