Magnetic heat capacity in lanthanum manganite single crystals

Lin, P.; Chun, Seung‐Hyun; Salamon, M. B.; Tomioka, Y.; Tokura, Y.

doi:10.1063/1.372535

Cited by 53 publications

(34 citation statements)

References 12 publications

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“…Lynn et al [30] conclude that La0.7Ca0.3MnO3 manganite does not exhibit a continuous second-order phase transition. This observation is also confirmed by Lin et al [31] when they clarify the breakdown of critical scaling in La0.7Ca0.3MnO3 owing to a transition that is not an ordinary second-order ferromagnetic transition. Recently, Bonilla et al [32] observed a breakdown of the universal behaviour for La2/3Ca1/3MnO3, which is a sign of the first-order nature of the phase.…”

Section: Resultssupporting

confidence: 73%

Critical Behavior of La0.8Ca0.2Mn1−xCoxO3 Perovskite (0.1 ≤ x ≤ 0.3)

et al. 2017

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Abstract:The critical properties of La 0.8 Ca 0.2 Mn 1−x Co x O 3 (x = 0, 0.1, 0.2 and 0.3) compounds were investigated by analysis of the magnetic measurements in the vicinity of their critical temperature. Arrott plots revealed that the paramagnetic PM-ferromagnetic (FM) phase transition for the sample with x = 0 is a first order transition, while it is a second order transition for all doped compounds. The critical exponents β, γ and δ were evaluated using modified Arrott plots (MAP) and the Kouvel-Fisher method (KF). The reliability of the evaluated critical exponents was confirmed by the Widom scaling relation and the universal scaling hypothesis. The values of the critical exponents for the doped compounds were consistent with the 3D-Heisenberg model for magnetic interactions. For x = 0.1, the estimated critical components are found inconsistent with any known universality class. In addition, the local exponent n was determined from the magnetic entropy change and found to be sensitive to the magnetic field in the entire studied temperature range.

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Section: Resultssupporting

confidence: 73%

Critical Behavior of La0.8Ca0.2Mn1−xCoxO3 Perovskite (0.1 ≤ x ≤ 0.3)

et al. 2017

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“…13. The fitting agrees quite well with the experimental results, Lofland et al [12] 0.45 Gosh et al [14] 0.37 1.22 Vasiliu-Doloc et al [15] 0.30 Martin et al [16] 0.295 Oleaga et al [18] +0.11 Lin et al [19] 0 Ho et al [45] 0.521 0.912 Jiang et al [27] 0.37 1.38 though not as nicely as in the previous sample; the obtained parameters are α = 0.10 ± 0.02, A + /A − = 0.52, having used a fitting range of 4.8 × 10 −2 − 9.4 × 10 −3 for t < T C and 4.6 × 10 −2 − 1.1 × 10 −4 for t > T C . It was also confirmed that the theoretical Heisenberg parameters did not allow the fitting of the curve.…”

Section: B Nd 06 Sr 04 Mnosupporting

confidence: 80%

Three-dimensional Ising critical behavior inR0.6Sr0.4MnO3(R

2015

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Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher statement: © 2015 American Physical Society A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription. All these values agree with the three-dimensional (3D)-Ising universality class (α = 0.11, β = 0.3265, γ = 1.237, and δ = 4.79) and are very far away from any other known universality class. This suggests the presence of magnetocrystalline anisotropies in the system that must be taken into account to fully describe the magnetism of these manganites, which deviates from a simple double exchange model.

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“…Among these are the failure of the magnetic correlation length to increase strongly as the transition temperature T C is approached from above, the persistence of a well defined spin-wave dispersion close to the transition [1], and an unusual shift in the heat capacity peak to higher temperatures in applied magnetic fields. [2] An explanation of this unusual behavior of the heat capacity in the context of a Griffiths singularity [3] is the focus of the present paper.…”

mentioning

confidence: 99%

“…The sharpness of the zero field data might signal a first-order transition, but there is no evidence of hysteresis. The shift in the heat capacity peak is uncharacteristic of ferromagnetic transitions, as discussed previously [2]. To treat this behavior, we employ a modified version of the Oguchi cluster method [27], a simple improvement to mean-field theory.…”

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confidence: 99%

Colossal Magnetoresistance is a Griffiths Singularity

2002

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It is now widely accepted that the magnetic transition in doped manganites that show large magnetoresistance is a type of percolation effect. This paper demonstrates that the transition should be viewed in the context of the Griffiths phase that arises when disorder suppresses a magnetic transition. This approach explains unusual aspects of susceptibility and heat capacity data from a single crystal of La0.7Ca0.3MnO3.The term "colossal magnetoresistance" (CMR) has commonly been used to describe the very large, magneticfield driven changes in electrical resistivity in oxides based on LaMnO 3 near their second-order, ferromagnetic transitions. The largest CMR effects are accompanied by other anomalies in magnetic and thermodynamic properties. Among these are the failure of the magnetic correlation length to increase strongly as the transition temperature T C is approached from above, the persistence of a well defined spin-wave dispersion close to the transition [1], and an unusual shift in the heat capacity peak to higher temperatures in applied magnetic fields.[2] An explanation of this unusual behavior of the heat capacity in the context of a Griffiths singularity [3] is the focus of the present paper.There is now general consensus that the CMR transition is a type of percolation in which, due to the doubleexchange process [4], bonds become metallic as neighboring spins tend to align. The strength of the CMR effect (along with the transition temperature) depends strongly on the ionic size and concentration of the divalent atom that substitutes for La in LaMnO 3 . The effect is nearly absent for La 2/3 Sr 1/3 MnO 3 (T C = 360 K) but quite strong in the present sample La 0.7 Ca 0.3 MnO 3 (T C = 218 K) [5]. In the low temperature metallic phase, the exchange interactions, as measured by the spin-wave stiffness, are the same in Sr-snd Ca-doped crystals [6], demonstrating that the key to the CMR effect is to be found in the non-metallic regime. The ionic size of the divalent substituent exerts its effect on magnetic and electronic properties through local tilting of the oxygen octahedra [7] and the concurrent bending of the active Mn-OMn bonds. This inhibits the formation of metallic bonds and leads to charge localization, polaron formation, and possible charge segregation [8,9]. Evidence in favor of a percolation picture comes from a Monte-Carlo simulation of a random field Ising model that assigns conductivity zero and unity to bonds between neighboring antiparallel and parallel spins respectively [10]. It both produces CMR and emphasizes the importance of randomness. Experimental evidence was provided by Jaime et al.[11] who extracted the field and temperature dependent metallic-bond concentration c(H, T ) from the resistivity via the effective medium approximation, and showed that it also describes the thermoelectric power data. Direct evidence for coexisting polaronic/insulating and metallic components have been reported from neutron [12] Discussions of the CMR effect in percolation terms [16][17][18] have gener...

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Magnetic heat capacity in lanthanum manganite single crystals

Cited by 53 publications

References 12 publications

Critical Behavior of La0.8Ca0.2Mn1−xCoxO3 Perovskite (0.1 ≤ x ≤ 0.3)

Critical Behavior of La0.8Ca0.2Mn1−xCoxO3 Perovskite (0.1 ≤ x ≤ 0.3)

Three-dimensional Ising critical behavior inR0.6Sr0.4MnO3(R

Colossal Magnetoresistance is a Griffiths Singularity

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