Superconductivity and normal state resistivity of Ba0.6K0.4BiO3: an optical phonon approach

Varshney, Dinesh; Shah, Sanjay; Singh, Rajiv K.

doi:10.1006/spmi.1998.0603

Cited by 6 publications

(2 citation statements)

References 22 publications

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“…The additional term due to the electron-electron contribution was required in understanding the resistivity behaviour, as extensive attempts to fit the data with residual resistivity and phonon resistivity were unsuccessful. The power temperature dependence of ρ diff on electron-electron scattering was also earlier noticed in hole-doped manganites [15], cuprates [17], bismuth oxides [18], doped fullerides [19], diborides [20] and intermetallic alloys [21]. The departure from electron-phonon-induced resistivity behaviour could be ascribed to either the change in dimensionality or the change in carrier density.…”

Section: Electrical Resistivitysupporting

confidence: 63%

Effect of electron/hole doping on the transport properties of lanthanum manganites LaMnO₃

Varshney

Mansuri

Kaurav

2007

J. Phys.: Condens. Matter

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We report the results of electrical resistivity, magnetic susceptibility and thermoelectric power measurements on the stoichiometric hole-doped La(0.8)Ca(0.2)MnO(3) and electron-doped La(0.8)Ce(0.2)MnO(3) manganites. The resistivity and thermopower data show a metal-insulator phase transition for both samples. Magnetic susceptibility measurement confirms that both the samples undergo a transition from paramagnetic to ferromagnetic phase at defined Curie temperatures T(c) = 240 K (La(0.8)Ca(0.2)MnO(3)) and 263 K (La(0.8)Ce(0.2)MnO(3)). The electrical resistivity data are then theoretically analysed within the framework of the classical electron-phonon model of resistivity, i.e. the Bloch-Gruneisen model. Detailed analysis of the electrical resistivity of electron- and hole-doped manganites suggests that besides the electron-phonon effect another possibility for the change in carrier density arises due to the presence of electron correlation in the metallic system. From the thermopower S(T) results, we suggest that its behaviour is determined by competition among the several operating scattering mechanisms for the heat carriers and a balance between carrier diffusion and phonon drag contributions in the polycrystalline samples of hole-doped La(0.8)Ca(0.2)MnO(3) and electron-doped La(0.8)Ce(0.2)MnO(3) manganites.

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Section: Electrical Resistivitysupporting

confidence: 63%

Effect of electron/hole doping on the transport properties of lanthanum manganites LaMnO₃

Varshney

Mansuri

Kaurav

2007

J. Phys.: Condens. Matter

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“…The additional term due to the electron-electron contribution was required in understanding the resistivity behaviour, as extensive attempts to fit the data with residual resistivity and phonon resistivity were unsuccessful. The power temperature dependence of ρ dif with electron-electron scattering was also earlier noticed in copper oxides [10], bismuth oxides [11], doped fullerides [12], and sulfides like TiS 2 [13]. The departure from electron-phonon induced resistivity behaviour could be ascribed to either the change in dimensionality or the change in carrier density/mobility.…”

Section: Electrical Resistivitysupporting

confidence: 60%

The effect of Al/Si ratio on the transport properties of the layered intermetallic compound CaAl₂Si₂

Kuo¹,

Sivakumar²,

Tasi³

et al. 2007

J. Phys.: Condens. Matter

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We report the results of the electrical resistivity and Seebeck coefficient as well as thermal conductivity measurements on the stoichiometric CaAl(2)Si(2) and non-stoichiometric CaAl(1.75)Si(2.25), CaAl(1.9)Si(2.1), CaAl(2.1)Si(1.9), and CaAl(2.25)Si(1.75) compounds in the temperature range 10-300 K. It has been found that the magnitude of electrical resistivity decreases for the non-stoichiometric samples, attributed to the shift of Fermi energy from the dip of the density of states as a consequence of the changed Si/Al content. In addition, a systematic change in the magnitude of Seebeck coefficient as a function of Al/Si concentration has been observed. The results have been associated with the effect of hole/electron doping on the Fermi level density of states. A detailed analysis of the electrical resistivity and Seebeck coefficient suggests the presence of two types of charge carrier and the temperature dependent changes in their mobility. From the thermal conductivity results, we correlated the extent of disorder and Al/Si ratio with various thermal scattering mechanisms in the investigated temperature range.

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Superconducting pairing and the two-gap nature of Al and C doped MgB₂: screened phonon-pairing mechanism

Varshney¹,

Nagar²,

Bhatnagar³

et al. 2010

Supercond. Sci. Technol.

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A simplified two-band model for describing the longitudinal dielectric function for a layered MgB 2 system has been developed to reveal the attractive pairing mechanism leading to the superconducting state. A model dielectric function for σ and π band carriers is set up that fulfils the appropriate sum rules on the electronic and ionic polarizabilities. The value of the in-layer electron-phonon coupling strength and the Coulomb screening parameter for σ (π ) band carriers is obtained from the residues of the dielectric function. It is noticed that the σ -holes in the two-dimensional boron planes via the screened phonon coupling is responsible for the attractive interaction and the superconductor is in the strong coupling regime. Within this framework, the superconducting transition temperature T c of MgB 2 is estimated as 42 K and the pressure derivative of T c is negative. The isotope effect, coherence length, magnetic penetration depth, and volume derivative of T c are also estimated to be consistent with the earlier results. Within the two-band model of superconductivity in MgB 2 , we place particular emphasis on intraband channels, carriers either in σ or π bands, as interband effects are negligible. In such a situation the superconductivity originates from either σ or π band carriers. The implications of the effective interactive potential with both σ and π carriers and its analysis are discussed.

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Superconductivity and normal state resistivity of Ba0.6K0.4BiO3: an optical phonon approach

Cited by 6 publications

References 22 publications

Effect of electron/hole doping on the transport properties of lanthanum manganites LaMnO₃

Effect of electron/hole doping on the transport properties of lanthanum manganites LaMnO₃

The effect of Al/Si ratio on the transport properties of the layered intermetallic compound CaAl₂Si₂

Superconducting pairing and the two-gap nature of Al and C doped MgB₂: screened phonon-pairing mechanism

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Superconductivity and normal state resistivity of Ba0.6K0.4BiO3: an optical phonon approach

Cited by 6 publications

References 22 publications

Effect of electron/hole doping on the transport properties of lanthanum manganites LaMnO3

Effect of electron/hole doping on the transport properties of lanthanum manganites LaMnO3

The effect of Al/Si ratio on the transport properties of the layered intermetallic compound CaAl2Si2

Superconducting pairing and the two-gap nature of Al and C doped MgB2: screened phonon-pairing mechanism

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Product

Resources

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Effect of electron/hole doping on the transport properties of lanthanum manganites LaMnO₃

Effect of electron/hole doping on the transport properties of lanthanum manganites LaMnO₃

The effect of Al/Si ratio on the transport properties of the layered intermetallic compound CaAl₂Si₂

Superconducting pairing and the two-gap nature of Al and C doped MgB₂: screened phonon-pairing mechanism