Tunnel-type giant magnetoresistance in the granular perovskite<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">La</mml:mi></mml:mrow><mml:mrow><mml:mn>0.85</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mrow><mml:mn>0.15</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">MnO</mml:mi></mml:mrow><mm

Zhang, Ning; Ding, Weiping; Wang, Zhong; Xing, D. Y.; Du, Youwei

doi:10.1103/physrevb.56.8138

Cited by 338 publications

(182 citation statements)

References 21 publications

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“…In our previous paper [33], in order to describe the electrical -and magneto -transport properties of this same series of nanometric LCMO samples, we have considered core-shell structure of the nanoparticles. Practically, when the size of the manganites grain reduces to few tens of nanometers, we can assign a core-shell structure to them [4,14,27]. In fact, due to the nanometric grain size of our manganites samples, the surface-to-volume ratio is sufficiently large and, as a result, the following physical effects are most likely to take place in a higher degree.…”

Section: Results and Discussion A) Structural Characterization mentioning

confidence: 99%

Enhanced grain surface effect on magnetic properties of nanometric La0.7Ca0.3MnO3 manganite: Evidence of surface spin freezing of manganite nanoparticles

Dey

Nath

Manna

et al. 2008

Journal of Applied Physics

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We have investigated the effect of nanometric grain size on magnetic properties of single phase, nanocrystalline, granular La 0.7 Ca 0.3 MnO 3 (LCMO) sample. We have considered core-shell structure of our LCMO nanoparticles, which can explain its magnetic properties. From the temperature dependence of field cooled (FC) and zero-field cooled (ZFC) dc magnetization (DCM), the magnetic properties could be distinguished into two regimes: a relatively high temperature regime T > 40 K where the broad maximum of ZFC curve (at T = T max ) is associated with the blocking of core particle moments, whereas the sharp maximum (at T = T S ) is related to the freezing of surface (shell) spins. The unusual shape of M (H) loop at T = 1.5 K, temperature dependent feature of coercive field and remanent magnetization give a strong support of surface spin freezing that are occurring at lower temperature regime (T < 40 K) in this LCMO nanoparticles. Additionally, waiting time (t w ) dependence of ZFC relaxation measurements at T = 50 K show weak dependence of relaxation rate [S(t)] on t w and dM/dln(t) following a logarithmic variation on time. Both of these features strongly support the high temperature regime to be associated with the blocking of core moments.2 At T = 20 K, ZFC relaxation measurements indicates the existence of two different types of relaxation processes in the sample with S(t) attaining a maximum at the elapsed time very close to the wait time t w = 1000 sec, which is an unequivocal sign of glassy behavior.This age-dependent effect convincingly establish the surface spin freezing of our LCMO nanoparticles associated with a background of superparamagnetic (SPM) phase of core moments.

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Section: Results and Discussion A) Structural Characterization mentioning

confidence: 99%

Enhanced grain surface effect on magnetic properties of nanometric La0.7Ca0.3MnO3 manganite: Evidence of surface spin freezing of manganite nanoparticles

Dey

Nath

Manna

et al. 2008

Journal of Applied Physics

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“…For this class of materials, lower sintered temperatures (T s ) will be necessary as the grain size increases with T s . The effect of grain size on structural, magnetic and transport properties in hole-doped manganites has been extensively investigated [11][12][13][14][15][16][17]. All these researches indeed suggest that the magnetic properties are markedly affected by grain size.…”

mentioning

confidence: 99%

The effect of grain size on electrical transport and magnetic properties of La0.9Te0.1MnO3

Yang

Zhao

Zhang

et al. 2004

Solid State Communications

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The effect of grain size on structural, magnetic and transport properties in were dissolved in diluted nitric acid in which an excess of citric acid and ethylene glycol was added to make a metal complex. After all the reactants had completely dissolved, the solution was mixed and heated on a hot plate resulting in the formation of a gel. The gel was dried at 250 °C, and then preheated to 600 °C to remove the remaining organic and to decompose the nitrates of the gel. The resulting powder was pressed into pellets, each of which was sintered at a different temperature (T s = 800 °C, 900 °C and 1000 °C) in air. In order to obtain a polycrystalline reference pattern, The crystal structures were examined by x-ray diffractometer using Cu 4 α K radiation at room temperature. The magnetic measurements were carried out with a Quantum Design superconducting quantum interference device (SQUID) MPMS system (2 ≤T≤400 K, 0 ≤ H ≤5 T). Both zero-field-cooling (ZFC) and field-cooling (FC) data were recorded. The resistance was measured by the standard four-probe method from 25 to 300 K. ACKNOWLEDGMENTS

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“…1-5͒ and, more broadly, lanthanum manganites doped with other monovalent on divalent ions on either the A or the B site. [8][9][10][11]20,21 Various explanations have been advanced for this rich structure reported in the R-T curves in the lanthanum manganites including grain-size effects, 22 oxidation, 23 percolative phase separation, 24 and phase inhomogeneity. 4 In the present case, it is thought to arise from the grain boundaries in the sample.…”

mentioning

confidence: 99%