Interpretation of temperature dependence of the in-plane electrical resistivity in YBa2Cu4O8: Electron-phonon approach

In this paper, we undertake a quantitative analysis of observed temperature-dependent in-plane normal state electrical resistivity of single crystal YBa2Cu4O8. The analysis is within the framework of classical electron-phonon i.e., Bloch-Gruneisen model of resistivity. It is based on the inherent acoustic (low frequency) phonons (ωac) as well as high frequency optical phonons (ωop), the contributions to the phonon resistivity were first estimated. The optical phonons of the oxygen breathing mode yields a relatively larger contribution to the resistivity compared to the contribution of acoustic phonons. Estimated contribution to in-plane electrical resistivity 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 [80 ⩽ T ⩽ 300]. Quadratic temperature dependence of ρdiff. = [ρexp − {ρ0 + ρe−ph (=ρac + ρop)}] is understood in terms of electron-electron inelastic scattering. The relevant energy gap expressions within the Nambu-Eliashberg approach are solved imposing experimental constraints on their solution (critical temperature Tc). It is found that the indirect-exchange formalism provides a unique set of electronic parameters [electron-phonon (λph), electron-charge fluctuations (λpl), electron-electron (μ) and Coulomb screening parameter (μ*)] which, in particular, reproduce the reported value of Tc.