Effect of disorder on the thermodynamic phase transition in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">La</mml:mi><mml:mn>0.70</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">Ca</mml:mi><mml:mn>0.30</mml:mn></mml:msub><mml:mi mathvariant="normal">Mn</mml:mi><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Souza, J. A.; Neumeier, J. J.; Jardim, R. F.

doi:10.1103/physrevb.75.012412

Cited by 7 publications

(5 citation statements)

References 20 publications

(21 reference statements)

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“…Solid lines are drawn as guides to the eye. = 250 K. 27 Above this temperature, a semiconducting-like behavior ͓d͑T͒ / dT Ͻ 0͔ is observed in the whole studied temperature range. A sharp drop in when the system undergoes the structural phase transition at T S ϳ 710 K is evident.…”

Section: Resultsmentioning

confidence: 93%

Polaron liquid-gas crossover at the orthorhombic-rhombohedral transition of manganites

et al. 2008

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High-resolution synchrotron x-ray powder diffraction in La 0.7 Ca 0.3 MnO 3 shows in detail a first-order structural phase transition from orthorhombic ͑space-group Pnma͒ to rhombohedral ͑space-group R3c͒ crystal structures near T S = 710 K. Magnetic susceptibility measurements show that the rhombohedral phase strictly obeys the Curie-Weiss law as opposed to the orthorhombic phase. A concomitant change in the electrical resistivity behavior, consistent with an alteration from nonadiabatic to adiabatic small polaron hopping regimes, was also observed at T S . The simultaneous change in transport and magnetic properties are identified as a transition from a correlated polaron liquid for T Ͻ T S to an uncorrelated polaron gas for T Ͼ T S , driven by the change in the crystal symmetry.

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Section: Resultsmentioning

confidence: 93%

Polaron liquid-gas crossover at the orthorhombic-rhombohedral transition of manganites

et al. 2008

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“…The antiferromagnetic orders of these systems were observed by NMR measurements but the thermal anomalies are absent around the corresponding temperatures [18]. The missing entropy problem of the magnetic insulating systems with strong electron correlation is also the case in several intermetallic compounds such as La 2 CuO 4 known as a mother material of high-T c superconductors [19] and Y-doped La 0.7 Ca 0.3 MnO 3 [20], etc. The local disorders due to the substitution, possible frustrations of competing interactions, and a coupling with other degrees of freedom seem to give a pronounced influence on the long-range character of the 3D magnetic transitions.…”

Section: Resultsmentioning

confidence: 96%

Spin ordering and enhancement of electronic heat capacity in an organic system of (DI-DCNQI)₂(Ag_1−xCu_x)

Okuma

Nakazawa

Oguni

et al. 2008

J. Phys.: Condens. Matter

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Thermodynamic measurements on the organic system of (DI-DCNQI)(2)(Ag(1-x)Cu(x)) (x = 0,0.05, 0.71, 0.90) were performed to study the change from the charge-ordered (CO) insulating state to the π-d hybridized metallic state. A thermal anomaly associated with the antiferromagnetic transition that occurred in the charge-ordered lattice was observed at 6.2 K from the temperature dependence of the heat capacity of (DI-DCNQI)(2)Ag. We have found that the magnetic entropy around the peak is only 1.5% of Rln2, corresponding to the full entropy expected for the formula unit of (DI-DCNQI)(2)Ag. This anomaly is suppressed down to about 3 K in the x = 0.05 sample owing to the disorders induced in the CO lattice. In the metallic concentration of x = 0.90, the low-temperature electronic heat capacity coefficient, γ was found to be enhanced by up to about 63.6 mJ K(-2) mol(-1) probably owing to the cooperative effect of π-d hybridization and intersite Coulomb interaction (V).

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“…The results reveal the absence of a conventional phase transition close to T N ≈ 246 K, that is, the entropy is not removed when the disordered PM phase changes to an ordered magnetic state. Interestingly, structural disorder caused by the presence of random local strain fields promotes competition between magnetic interactions suppressing the expected peak in the molar heat capacity measurements …”

Section: Results and Discussionmentioning

confidence: 99%

Insulator–Metal Transition in the Nd₂CoFeO₆ Disordered Double Perovskite

et al. 2020

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A comprehensive study on the correlations of structural, magnetic, and electronic properties of a new disordered Nd2CoFeO6 double perovskite has been conducted. The lack of strong divergence of the magnetic susceptibility suggests competition between magnetic interactions at the magnetic phase transition T N = 246 K, which is confirmed by the absence of a heat capacity peak. The magnetic susceptibility results indicate that the Fe/Co spins form a classical noninteracting paramagnetic state above T ≈ 2.2T N, while deviations are found at intermediate temperatures indicating the presence of strong short-range magnetic interactions. AC and DC electrical resistivity results reveal a melting of insulating polaronic behavior to a metallic-like conductivity, establishing an electronic crossover closely related to both local magnetic moment and lattice-parameter evolution. We show from density functional calculations that the magnetic configurations have a strict relation to this crossover, being associated to a transition from low to high spin states of Co3+ ions. This insulator–metal transition has its origin driven by a local increase in the magnetic moment of Co3+ ions. Our results point to a scenario in which a continuous spin-state transition triggers a crossover between distinct electronic states from the insulating polaronic behavior to permanent metallic states.

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Effect of disorder on the thermodynamic phase transition inLa0.70Ca0.30MnO3

Cited by 7 publications

References 20 publications

Polaron liquid-gas crossover at the orthorhombic-rhombohedral transition of manganites

Polaron liquid-gas crossover at the orthorhombic-rhombohedral transition of manganites

Spin ordering and enhancement of electronic heat capacity in an organic system of (DI-DCNQI)₂(Ag_1−xCu_x)

Insulator–Metal Transition in the Nd₂CoFeO₆ Disordered Double Perovskite

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Effect of disorder on the thermodynamic phase transition inLa0.70Ca0.30MnO3

Cited by 7 publications

References 20 publications

Polaron liquid-gas crossover at the orthorhombic-rhombohedral transition of manganites

Polaron liquid-gas crossover at the orthorhombic-rhombohedral transition of manganites

Spin ordering and enhancement of electronic heat capacity in an organic system of (DI-DCNQI)2(Ag1−xCux)

Insulator–Metal Transition in the Nd2CoFeO6 Disordered Double Perovskite

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Spin ordering and enhancement of electronic heat capacity in an organic system of (DI-DCNQI)₂(Ag_1−xCu_x)

Insulator–Metal Transition in the Nd₂CoFeO₆ Disordered Double Perovskite