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Varshney, Dinesh; Patel, G S; Singh, Rajiv K.

doi:10.1023/a:1004684619579

Cited by 7 publications

(6 citation statements)

References 23 publications

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“…In order to estimate the zero limited resistivity, we use the experimental values of H c2 (0) = 80 T [28] and T c = 25 K [1]. Earlier, we developed an effective 2D effective interaction potential for electron-doped cuprates by considering both inter-layer and intra-layer interactions [18]. The physics to bear in mind is the consideration of two electrons interacting with boson fields and repelling each other through a Coulomb force within the CuO 2 plane.…”

Section: Resultsmentioning

confidence: 99%

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Interpretation of temperature-dependent resistivity of electron-doped cuprates

Varshney¹,

Choudhary²,

Singh³

2002

Supercond. Sci. Technol.

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The temperature-dependent normal state resistivity of single-crystal Nd1.85Ce0.15CuO4−δ is theoretically analysed within the framework of the classical electron–phonon model of resistivity, i.e. the Bloch–Gruneisen model. Due to inherent acoustic (low-frequency) phonons (ωac) as well as high-frequency optical phonons (ωop), the contributions to the resistivity have first been estimated. The optical phonons of the oxygen-breathing mode yield a relatively larger contribution to the resistivity compared to the contribution of acoustic phonons. The contribution to resistivity estimated by considering both phonons, i.e. ωac and ωop, along with the zero limited resistivity, when subtracted from single-crystal data, infers a quadratic temperature dependence over most of the temperature range (25 ≤ T ≤ 300 K). The quadratic temperature dependence of ρdiff = [ρexp − {ρ0 + ρe-ph( = ρac + ρop)}] is understood in terms of electron–electron inelastic scattering. The comparison of single-crystal experimental data with the present analysis appears to be favourable.

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Section: Resultsmentioning

confidence: 99%

“…The x-y plane containing the a-and b-axes is taken to lie in the CuO 2 layer, with the c-axis lying along the z-direction [18].…”

Section: The Modelmentioning

confidence: 99%

Interpretation of temperature-dependent resistivity of electron-doped cuprates

Varshney¹,

Choudhary²,

Singh³

2002

Supercond. Sci. Technol.

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“…Organosolv lignin is obtained by treatment of wood or bagasse, the fibrous residue that remains after plant material (i.e., sugar cane) is crushed to extract juice or sap, with various organic solvents . The Alcell process, no longer operational but previously demonstrated at a Repap Alcell pilot plant, is the most well-known process in the organosolv lignin category, and it involved dissolution of lignin in either ethanol or ethanol/water mixtures. − Lignol Energy Corporation in Canada recently modified the pretreatment developed at the Repap Alcell pilot plant and began operation of a pilot plant to again produce organosolv lignin of high purity and potentially high value . The principle advantages of the organosolv process is that it forms separate streams of cellulose, hemicelluloses, and lignin, allowing valorization of all components of lignocellulosic biomass, and the process is generally considered environmentally friendly because it does not use the sulfides and harsh conditions used in the kraft or lignosulfonate processes.…”

Section: Lignin Structure Pretreatment and Use In The Biorefinerymentioning

confidence: 99%

The Catalytic Valorization of Lignin for the Production of Renewable Chemicals

et al. 2010

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“…(0) ≈ 4.0 meV, T c = 25 K, Ze = −2e, d = 6.0 Å, N = 0.04, ε F = 0.22 eV, ε ∞ = 3.5 and m * = 3m e , [32] respectively for Nd 1.85 Ce 0.15 CuO 4 superconductor. The analysis of the elastic carrier-impurity contribution to the thermal conductivity is documented below.…”

Section: Resultsmentioning

confidence: 95%

“…These are indeed free parameters for phonon thermal conductivity in the present model and their physical interpretation is discussed later on. The length of the sample is about 3 mm and v s = 7 × 10 5 cm s −1 [32]. In the model Hamiltonian, it is presumed that the high-T c Nd 1.85 Ce 0.15 CuO 4 superconductors contain defects, phonons, and BCS-like quasi-particles, interacting with one another.…”

Section: Resultsmentioning

confidence: 99%

Effect of impurity scatterers on phonon, electron and magnon thermal transport in electron doped cuprate superconductors

Varshney¹

2006

Supercond. Sci. Technol.

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A theoretical model is evolved to account for the anomalies reported for the thermal conductivity (κ) of the electron doped cuprate superconductor Nd1.85Ce0.15CuO4. The lattice thermal conductivity by incorporating the scattering of phonons with defects, grain boundaries, electrons, and phonons in the model Hamiltonian is evaluated as a first step. Later on, the scattering of electrons with impurities for both s and d wave symmetry of the order parameter is also analysed. As a next step, the scattering of magnons with phonons, defects, grain boundaries and magnons is investigated in order to assess their role in thermal conduction. It is noticed that at very low temperatures (T<10 K), κ increases and shows almost T3/2 dependence on the temperature, which is attributed to spin-wave transport. However, the inclusion of phonon–impurity and the carrier–impurity scattering reduces the temperature dependence of κ and a power temperature dependence is revealed for T<10 K. Further, at Tc, κ develops a broad peak and then decreases as the temperature is increased. The anomaly in the vicinity of Tc and above its value is well accounted for in terms of interaction among the phonon–impurity, the magnon–impurity and the carrier–impurity channels of thermal conductivity. Conclusively, the temperature dependence of thermal conductivity is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between electron, magnon and phonon contributions. Numerical analysis of thermal conductivity from the present model shows similar results to those revealed from experiments.

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Untitled

Cited by 7 publications

References 23 publications

Interpretation of temperature-dependent resistivity of electron-doped cuprates

Interpretation of temperature-dependent resistivity of electron-doped cuprates

The Catalytic Valorization of Lignin for the Production of Renewable Chemicals

Effect of impurity scatterers on phonon, electron and magnon thermal transport in electron doped cuprate superconductors

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