• 제목/요약/키워드: ${La_{0.7}}{Ca_{0.3}}{MnO_3}$

검색결과 63건 처리시간 0.03초

Ultraviolet Photoelectron spectroscopy Study of Colossal Magnetoresistive $La_{0.7-x}P_rxCa_{0.3}MnO_3$

  • Lee, Chang-Won;Hoon Koh;Noh, Han-Jin;Park, Jong-Hyurk;Kim, Hyung-Do;Moonsup Han;Oh, Se-Jung;Eom, dai-Jin;Noh, Tae-Won
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 1999년도 제17회 학술발표회 논문개요집
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    • pp.172-172
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    • 1999

  • Perovskite Manganese Oxide has been intensively investigated since the discovery of the colossal magnetoresistive(CMR) effect. In this paper, we studied the effect of temperature dependence and various doping dependence of rare earth site ions of La0.7-xPrxCa0.3MnO3 series using Ultraviolet Photoelectron spectroscopy(UPS). They show unusual temperature dependent features and the doped rare earth ions seem to affect the electron-phonon coupling strongly. We found clear evidence of metal-insulator transition from the spectral density at the Fermi level. but the transition temperature is lower than that deduced from transport measurements. Also we found that the spectral features change as time goes on implying that the surface of these materials is somewhat unstable in the vacuum. We can conclude from these results that the surface oxygen atoms correlated to the hopping electrons can escape from the material into the vacuum and that the surface state of these material is different from the bulk state.

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Relationship between transition temperature and magnetic entropy changes in manganite materials

  • Phan, Manh-Huong;Yu, Seong-Cho;A.N. Ulyanov
    • 한국자기학회:학술대회 개요집
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    • 한국자기학회 2002년도 동계연구발표회 논문개요집
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    • pp.121-121
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    • 2002

  • A theoretical consideration for entropy changes in a magnetic solid is given in a general manner and has been taken into account for such La$\sub$0.7/Ca$\sub$0.3-x/Ba$\sub$x/MnO$_3$(x = 0.12, 0.24, 0.3) compounds. The total entropy changes, in which the total entropy is decomposed into the magnetic, lattice, and electron entropies, are discussed in detail. (omitted)

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Effect of La0.7Sr0.3MnO3 addition on superconducting properties and local structure of (Bi, Pb)-2223 superconductor

  • M. A. Anugrah;R. P. Putra;J. Y. Oh;B. Kang
    • 한국초전도ㆍ저온공학회논문지
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    • 제25권2호
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    • pp.5-9
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    • 2023

  • The effect of La0.7Sr0.3MnO3 (LSMO) addition on the superconducting property of Bi1.6Pb0.4Sr2Ca2Cu3O10+δ ((Bi, Pb)-2223) polycrystalline samples was studied. LSMO (0.3 wt.% to 2.0 wt.%) added (Bi, Pb)-2223 samples were prepared by using a solid-state reaction method. The XRD analyses show that as the LSMO addition increases, the volume fraction of the Bi-2223 phase is gradually decreased. The critical temperature (Tc) exhibits a gradual decrease with a single transition as the LSMO amount increases up to 1.0 wt.%, but a further addition of LSMO induces an abrupt decrease of Tc with a dual transition. The analyses on the local structure of the CuO2 plane from the X-ray absorption fine structure (EXAFS) measurements showed that for the samples with low concentration of LSMO up to 1.0 wt.%, the Cu-O bond length and the CuO2 plane ordering do not degrade from the values of pure (Bi, Pb)-2223, while they get worsen with a further increase of LSMO addition. These results open up the possibility of LSMO as artificial pinning centers of the (Bi, Pb)-2223 system for power application.

  • https://doi.org/10.9714/psac.2023.25.2.005 인용 PDF