Temperature dependence of resistivity of RFeAsO compounds

Abstract

The resistivity (q) data for RFeAsO compounds (R = Ce, Pr, Nd, Sm), in the temperature (T) range 35-315 K have been analyzed to identify the dominant scattering mechanisms. Close to the room temperature, the system appears to be a metal with low electron density, and the electron-phonon scattering is the dominant one. At lower temperatures, electron-electron scattering plays an important role. In an intermediate temperature region, unlike metallic system, dq/dT is negative; and q -1 varies as ln T as in a state of weak localization. We look into the origin of negative dq/dT. The analysis of q(T) data below the SDW transition temperature shows the presence of electron-electron interaction in addition to a SDW energy gap, and also gives an estimate of the SDW energy gap.

High-Temperature Superconductors as Ionic Metals

“…Indeed, when scaled to the number of carriers, resistivity in the cuprates follows a pure T 2 law over a much wider temperature range [5] than in textbook Fermi liquids such as In or Al, where the T 2 contribution must in addition be disentangled from a Grüneisen crossover curve [53]. In the pnictides, a ∼ 100-K wide almost pure T 2 region is similarly found [54] at low temperatures.…”

“…Indeed, when scaled to the number of carriers, resistivity in the cuprates follows a pure T 2 law over a much wider temperature range [5] than in textbook Fermi liquids such as In or Al, where the T 2 contribution must in addition be disentangled from a Grüneisen crossover curve [53]. In the pnictides, a ∼ 100-K wide almost pure T 2 region is similarly found [54] at low temperatures. Despite all their differences, cuprates and pnictides seem to lie in a similar "sweet spot" for SC: a Fermi liquid, uncoupled from the lattice, scattering by a high-energy mechanism which does not slow down the free carriers.…”

Low Field Magnetic and Electric Transport Properties of LaFeAsO and Oxygen Deficiency of LaFeAsOx

“…Naturally, there may be other possible explanations for dq/dT < 0 behavior. For instance, Mukherjee et al 57 have reported the resistivity of RFeAsO (R = Ce, Pr, Nd, and Sm) compounds, and such a logarithmic increase of resistance has been interpreted as weak localization. 58 There is still considerable ambiguity with regard to the origin of this anomaly; however, it can be attributed to the presence of Kondo-like magnetic scattering between itinerant electrons and localized Fe moments in the vicinity of As-vacancies.…”

Magnetism of PrFeAsO parent compound for iron-based superconductors: Mössbauer spectroscopy study

“…High superconducting transition temperatures are assured by the presence of strongly internally coupled corrugated "twodimensional" iron-pnictogen layers separated by large distances one from another thanks to the complex and rather thick rare earth -oxygen layers. Fe-As layers are stacked in the normal order without inversion [8][9][10]. Compounds containing praseodymium as rare earth are particularly interesting due to the large localized magnetic moment of praseodymium with significant orbital contribution.…”