Giant oxygen isotope shift in the magnetoresistive perovskite La1–xCaxMnO3+y

Zhao, Guangyao; Conder, K.; Keller, H.; Müller, K. A.

doi:10.1038/381676a0

Cited by 671 publications

(472 citation statements)

References 15 publications

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“…An electronic microbalancer (Mitteler-Telado XL26) with 1 µg precision was used for sample weighting. The 18 O sample has 70%(±1%) 18 O and 30%(±1%) 16 O. To make sure the isotope exchange effect, back-exchange of 18 O sample by 16 O was carried out in the same way and the weight change recorded showed a complete backexchange.…”

Section: Experiments Detailsmentioning

confidence: 99%

“…No impurity phase was found in powder X-ray diffraction patterns. The oxygen-isotope enrichment is determined from the weight changes of both 16 O and 18 O samples. An electronic microbalancer (Mitteler-Telado XL26) with 1 µg precision was used for sample weighting.…”

Section: Experiments Detailsmentioning

confidence: 99%

“…Each piece was put into an alumina boat which was sealed in a quartz tube filled with 1 bar oxygen (one for 16 O and another for 18 O) mounted in a furnace. The quartz tubes formed parts of two identical closed loops.…”

Section: Experiments Detailsmentioning

confidence: 99%

“…In perovskite maganites, a study on the effect of substitution of 16 In cobalt oxides, electron-phonon coupling is also important to affect the transport and magnetic properties 1,2,3,9,10,11,12,13,14 . For example, the Co 3+ in IS state is also a Jahn-Teller active ion just like the Mn 3+ ion.…”

Section: Introductionmentioning

confidence: 99%

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Oxygen isotope effect on the spin-state transition in(Pr0.7Sm0.3)0.7Ca0.3CoO3

Wang

Luo

et al. 2006

Phys. Rev. B

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Oxygen isotope substitution is performed in the perovskite cobalt oxide (Pr0.7Sm0.3)0.7Ca0.3CoO3 which shows a sharp spin state transition from the intermediate spin (IS) state to the low spin (LS) state at a certain temperature. The transition temperature of the spin state up-shifts with the substitution of 16 O by 18 O from the resistivity and magnetic susceptibility measurements. The up-shift value is 6.8 K and an oxygen isotope exponent (αS) is about -0.8. The large oxygen isotope effect indicates strong electron-phonon coupling in this material. The substitution of 16 O by 18 O leads to a decrease in the frequency of phonon and an increase in the effective mass of electron (m * ), so that the bandwidth W is decreased and the energy difference between the different spin states is increased. This is the reason why the Ts is shifted to high temperature with oxygen isotopic exchange.

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Section: Experiments Detailsmentioning

confidence: 99%

Section: Experiments Detailsmentioning

confidence: 99%

Section: Experiments Detailsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Oxygen isotope effect on the spin-state transition in(Pr0.7Sm0.3)0.7Ca0.3CoO3

Wang

Luo

et al. 2006

Phys. Rev. B

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“…There are two effects that should lower the FN-PN transition temperature substantially, namely, (i) the fluctuations neglected in the mean-field theory and (ii) the dynamical JahnTeller coupling between electrons and phonons [31,32], which leads to the isotope effect [33]. The first is a well-known deficiency of the mean-field theories, while, in a recent study, we have shown that the second effect, namely, the dynamical Jahn-Teller coupling, leads to a reduction of the transition temperature by about a factor of three for the manganites [32].…”

Section: Introductionmentioning

confidence: 99%

Mean-field theory of charge ordering and phase transitions in the colossal-magnetoresistive manganites

Mishra

Pandit

Satpathy

1999

J. Phys.: Condens. Matter

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Abstract. We study phase transitions in the colossal-magnetoresistive manganites by using a mean-field theory both at zero and non-zero temperatures. Our Hamiltonian includes doubleexchange, superexchange, and Hubbard terms with on-site and nearest-neighbour Coulomb interaction, with the parameters estimated from earlier density-functional calculations. The phase diagrams show magnetic and charge-ordered (or charge-disordered) phases as a result of the competition between the double-exchange, superexchange, and Hubbard terms, the relative effects of which are sensitively dependent on parameters such as doping, bandwidth, and temperature. In accord with the experimental observations, several important features are reproduced from our model, namely, (i) a phase transition from an insulating, charge-ordered antiferromagnetic to a metallic, charge-disordered ferromagnetic state near dopant concentration x = 1/2, (ii) the reduction of the transition temperature T AF→F by the application of a magnetic field, (iii) melting of the charge order by a magnetic field, and (iv) phase coexistence for certain values of temperature and doping. An important feature, not reproduced in our model, is the antiferromagnetism in the electron-doped systems, e.g., La 1−x Ca x MnO 3 over the entire range of 0.5 x 1, and we suggest that a multi-band model which includes the unoccupied t 2g orbitals might be an important ingredient for describing this feature.

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