Electrical and magnetic properties of lead-substituted lanthanum ferrimanganites

Parfenov, V. V.; Bashkirov, Sh. Sh.; Valiullin, A. A.; Aver’yanov, A. V.

doi:10.1134/1.1131383

Cited by 3 publications

(4 citation statements)

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“…The magnitude of positive MR increases with temperature lowered, a positive MR of 20% being found at T ϭ4.2 K and Hϭ8 T. Large positive MR was reported at high temperatures in La 0.88 Sr 0.12 MnO 3 single crystals 19 and in a lead-substituted lanthanum ferrimanganate single crystal. 20 To our knowledge, however, never before has such a positive MR phenomenon been observed in the CMR ferromagnets at low temperatures.…”

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confidence: 94%

Positive magnetoresistance from quantum interference effects in perovskite-type manganites

Chen

Xing

2001

Phys. Rev. B

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Positive magnetoresistance ͑MR͒ in La 0.7 Pb 0.3 MnO 3 single crystals was observed between temperatures 4.2 and 50 K, in addition to the negative colossal magnetoresistance ͑CMR͒ at higher temperatures. The positive MR increases with temperature lowered and reaches 20% at Tϭ4.2 K in a magnetic field of Hϭ8 T. From temperature and field dependences of the resistivity, it follows that the positive MR at low temperatures arise from quantum interference effects ͑QIE͒. The QIE-induced MR observed in the CMR manganites indicates that the Coulomb interaction and disorder may play an important role in their transport properties.Magnetoelectronics is a hot topic in the condensed matter physics with wide technological applications. 1 An imbalance of electron spins can lead to spin-polarized transport; this in turn leads to the idea of electronic devices based not on electrons and holes driven by electric fields, but on spin-up and spin-down electrons biased and controlled by magnetic fields. Negative giant magnetoresistance ͑GMR͒ has been successively observed in magnetic multilayers and magnetic granular systems. 2,3 Such GMR effects are attributed to spindependent scattering at interfaces and in bulk ferromagnets. In a two-channel ͑spin up and down͒ current model, an applied magnetic field can induce a low-resistance or shortcircuit channel, resulting in a big drop in resistance. On the other hand, a negative CMR observed in perovskite-type ferromagnetic manganites 4,5 arises from the magnetic field suppressing the scattering of carriers by localized moments. Recently, Manyala et al. 6 found an anomalous positive MR in ferromagnet Fe 1Ϫy Co y Si and argued that it can arise by a different mechanism-the quantum interference effects ͑QIE͒ rather than simple scattering. It was emphasized that the Fe 1Ϫy Co y Si ferromagnets are disordered, low-carrierdensity magnets where the same electrons are responsible for both magnetic properties and electrical conduction. They are quite different from the CMR manganites in which the e g electrons are carriers responsible for the electrical conduction, while t 2g electrons form the local spins responsible for the magnetism and act as scattering sites for the conduction electrons. This argument seems to exclude the possibility of the QIE-induced positive MR occurring in the CMR manganites. In this paper, however, we find a QIE-induced positive MR in La 0.7 Pb 0.3 MnO 3 single crystals between temperatures 4.2 and 50 K, providing an interesting reverse example.The parent compound LaMnO 3 is an A-type antiferromagnetic insulator which consists of ferromagnetic ͑FM͒ planes ordered antiferromagnetically in the third direction. The insulating behavior of LaMnO 3 stems from the fact that there appears at most one e g electron at each Mn 3ϩ ion due to strong on-site Coulomb interactions. Upon doping with Pb 2ϩ ions on La 3ϩ sites, La 1Ϫx Pb x MnO 3 (0.25ϽxϽ0.4) becomes a mixed-valence oxide due to introduction of Mn 4ϩ and exhibits an FM metal ground state. 7 This manganite undergoes an FM me...

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confidence: 94%

Positive magnetoresistance from quantum interference effects in perovskite-type manganites

Chen

Xing

2001

Phys. Rev. B

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“…1). This differentiates the spectra of Tm 0.65 Sr 0.35 Fe x Mn 1 -x O 3 from those of the light lan thanide (lanthanum, neodymium, and europium) fer romanganites, which have only one doublet [2,4].…”

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confidence: 90%

“…The colossal magnetoresistance of perovskite structure 3d-4f metal oxides (rare earth manganites and cobaltites), discovered in the 1990s, is most likely due to magnetic phase separation in these materials [1]. Previously [2][3][4][5], Mössbauer spectroscopy was used to study the mag netic microstructure and magnetic and electrical prop erties of ferromanganites-solid solutions substituted in both the rare earth and 3d sublattices: 3 . It has been shown that the competition between ferro and antiferromagnetic interactions in these solid solutions is favorable for mag netic phase separation and formation of clusters that differ in magnetic order from the major part of the material (matrix).…”

Section: Introductionmentioning

confidence: 99%

“…Phase separation leads to a number of nontrivial mag netic and electrical properties. In particular, lead sub stituted lanthanum ferromanganites and strontium substituted europium ferromanganites with iron con centrations х 0.4 have a high positive magnetoresis tance near room temperature in relatively weak fields [2]. were first sintered in air at a temperature of 1220 K for 8 h. Next, the samples were reground and re pressed.…”

Section: Introductionmentioning

confidence: 99%

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