Magnetoresistance measurements on the magnetic semiconductor Nd0.5Pb0.5MnO3

Kusters, Rémy; Singleton, John; Keen, David A.; McGreevy, R.L.; Hayes, W.

doi:10.1016/0921-4526(89)90530-9

Cited by 819 publications

(375 citation statements)

References 11 publications

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“…However, as the temperature increases and approaches the Curie temperature T c a sudden increase of the resistivity is observed [3]. As the temperature dependence of the resistivity ρ(T ) has typically semiconducting behavior ( dρ/dT < 0) above T c , this increase in resistivity at around T c is usually desribed as a metal-insulator transition.…”

Section: Introductionmentioning

confidence: 99%

“…Upon doping with Sr, this perovskite oxide becomes a ferromagnetic metal; the connection between metallicity and ferromagnetism was well explained by the double exchange hopping mechanism [2]. The discovery of colossal magnetoresistance phenomena in samples with Sr dopant densities in the 0.2≤ x ≤0.4 regime [3] brought a revival of the interest to these sytems.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Orbital and charge ordering inPr1−xCa
Анисимов
¹
,
Elfimov
²
,
Korotin
³

et al. 1997
Phys. Rev. B
70
2
38
0
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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Orbital and charge ordering inPr1−xCa
Анисимов
¹
,
Elfimov
²
,
Korotin
³

et al. 1997
Phys. Rev. B
70
2
38
0
View full text Add to dashboard Cite

show abstract

“…Whereas spin disorder can contribute to the variations in the resistivity near T c , only more recently the role of electron-phonon interactions on the localization has been put in a clearer perspective. [5][6][7] This theoretical work was based on research on magnetic semiconductors like EuO, and only recently applied to doped LaMnO 3 . Still, it is not known if the metal insulator transition in doped LaMnO 3 is driven by changes in the carrier density or the mobility.…”

mentioning

confidence: 99%

Transport mechanisms in dopedLaMnO3:Evidence for polaron formation

Palstra

Ramirez²,

Cheong³

et al. 1997

Phys. Rev. B

172

103

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We report electrical transport experiments on the colossal magnetoresistance compound (La,Ca͒MnO 3 over a wide range of composition and temperature. Comparison of thermopower and electrical resistivity measurements above the metal-insulator transition indicate a transport mechanism not dominated by spin disorder, but by small polaron formation. Additionally, we find that in the high-temperature limit the thermopower corresponds to backflow of spin entropy, expected from motion of positively charged particles in a rigid Sϭ2 system, showing a remarkable independence of Sϭ3/2 particle density. ͓S0163-1829͑97͒09334-X͔The recent observation of large magnetoresistance effects in thin films of doped LaMnO 3 has renewed the interest in the metal-insulator transition in these materials. [1][2][3] Since the metal-insulator transition temperature, T MI , can be tuned to above room temperature, this opens possibilities to use this material not only for recording media but also for other types of magnetic switching applications. However, the emerging notion that magnetoresistance due to a metal-insulator transition decreases with increasing T MI , necessitates a better understanding of the underlying basic transport mechanism to exploit the magnetoresistive properties of these materials fully. The microscopic nature of the transport mechanism is condensed into the description of double exchange, the simultaneous electron transfer of an electron on a Mn atom to an O atom of the surrounding oxygen octahedron, and another electron from this O atom to a neighboring Mn atom. 4 This indirect exchange mechanism establishes, because of spin conservation in the exchange, a direct relation of the metallic state with the ferromagnetic coupling between the Mn spins. However, there is remarkably little known about the transport mechanism in the insulating state. Whereas spin disorder can contribute to the variations in the resistivity near T c , only more recently the role of electron-phonon interactions on the localization has been put in a clearer perspective. [5][6][7] This theoretical work was based on research on magnetic semiconductors like EuO, and only recently applied to doped LaMnO 3 . Still, it is not known if the metal insulator transition in doped LaMnO 3 is driven by changes in the carrier density or the mobility.In order to gain insight into the nature of the transport mechanism, we have performed thermopower measurements on doped LaMnO 3 over a wide range of concentrations and temperatures in addition to the basic characterization by electrical resistivity and magnetic measurements. Thermopower is in contrast to electrical resistivity relatively insensitive to effects of grain boundaries and disorder. We will show that for this material, thermopower provides unique insight into the transport mechanism. First, we show that the change of sign in the thermopower is not related to competition between electron and hole conduction, but accidental cancellation of the entropic term and the energy transport term of the thermopower...

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“…[1][2][3] This feature was the outbreak to highlight the strong interplay between charge, and orbital and magnetic properties exhibited by these compounds. Accordingly, they show a wide variety of electronic and magnetic phases.…”

Section: Introductionmentioning

confidence: 99%

Double stripe ordering inNd0.5Sr0.5MnO3determined by resonant soft x-ray scattering

et al. 2006

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We have studied the low-temperature ordered phase of Nd 0.5 Sr 0.5 MnO 3 by resonant soft x-ray scattering at the Mn L 2,3 edges. Strong resonances were observed at ͑ 0 1 2 0 ͒ and ͑ 1 2 0 0 ͒ reflections, which are resolved in momentum space. Azimuthal scans reveal a periodicity for both resonances, the minimum intensity being almost zero. The two reflections show a very different energy dependence which extends in the whole energy region of the Mn L-edge. The ͑ 0 1 2 0 ͒ reflection originates from the anisotropy induced on the d-symmetry projected density of states owing to the local tetragonal distortion at one of the two crystallographic inequivalent Mn sites ͑the so-called Mn 3+ ions in the conventional ionic description͒. This is similar to the resonance observed at the Mn K edge. We propose that the ͑ 1 2 0 0 ͒ reflection, which has not its counterpart either on the Mn K-edge resonant scattering or on the magnetic scattering, is originated by anisotropy of the d-symmetry projected density of the so-called Mn 4+ sublattice. In this way, the latter reflection could denote a pure orbital ordering in this sublattice.

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Magnetoresistance measurements on the magnetic semiconductor Nd0.5Pb0.5MnO3

Cited by 819 publications

References 11 publications

Orbital and charge ordering inPr1−xCa
Анисимов
¹
,
Elfimov
²
,
Korotin
³

et al. 1997
Phys. Rev. B
70
2
38
0
View full text Add to dashboard Cite

Orbital and charge ordering inPr1−xCa
Анисимов
¹
,
Elfimov
²
,
Korotin
³

et al. 1997
Phys. Rev. B
70
2
38
0
View full text Add to dashboard Cite

Transport mechanisms in dopedLaMnO3:Evidence for polaron formation

Double stripe ordering inNd0.5Sr0.5MnO3determined by resonant soft x-ray scattering

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Magnetoresistance measurements on the magnetic semiconductor Nd0.5Pb0.5MnO3

Cited by 819 publications

References 11 publications

Orbital and charge ordering inPr1−xCaАнисимов1, Elfimov2, Korotin3 et al. 1997Phys. Rev. B702380View full textAdd to dashboardCite

Orbital and charge ordering inPr1−xCaАнисимов1, Elfimov2, Korotin3 et al. 1997Phys. Rev. B702380View full textAdd to dashboardCite

Transport mechanisms in dopedLaMnO3:Evidence for polaron formation

Double stripe ordering inNd0.5Sr0.5MnO3determined by resonant soft x-ray scattering

Contact Info

Product

Resources

About

Orbital and charge ordering inPr1−xCa
Анисимов
¹
,
Elfimov
²
,
Korotin
³

et al. 1997
Phys. Rev. B
70
2
38
0
View full text Add to dashboard Cite

Orbital and charge ordering inPr1−xCa
Анисимов
¹
,
Elfimov
²
,
Korotin
³

et al. 1997
Phys. Rev. B
70
2
38
0
View full text Add to dashboard Cite