Resistivity saturation in PrFeAsO1−xFysuperconductor: evidence of strong electron–phonon coupling

Bhoi, Dilip; Mandal, P.; Choudhury, Pranab

doi:10.1088/0953-2048/21/12/125021

Cited by 30 publications

(47 citation statements)

References 39 publications

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“…This mismatch between the electron-phonon coupling constant λ and the expected T c is similar to calculations done on several 1111 pnictides where λ ∼ 0.17 − 0.21 predict a T c of a few Kelvin at most 32 . A λ tr ∼ 0.12 is also much smaller than the λ tr = 1.53 reported for PrFeAsO 1 . The MIR limit is a stronger indication of charge carrier coupling to phonon excitations.…”

Section: Discussioncontrasting

confidence: 55%

“…However, the cuprate superconductors are doped Mott-Hubbard insulators with strong Coulomb interactions, whereas the pnictide parent compounds are metallic, suggesting that the pnictides might be more weakly correlated than the cuprates. Supporting this picture, resistivity saturation has been reported in PrFeAsO crystals as evidence for electron-phonon scattering 1 . However, magnetic susceptibility in BaFe 2−x Co x As 2 has been observed to show unusual linear temperature dependence up to 700 K, described as indicating strong magnetic fluctuations 2 .…”

Section: Introductionmentioning

confidence: 75%

“…Large resistivities have been observed in the NdFeAsO 33 and LaFePO 34 systems and a resistivity saturation at 2500 − 3000 µΩ·cm has been reported in PrFeAsO crystals as evidence for a MIR limit 1 . This saturation is significantly higher that the 100 − 1000 µΩ·cm seen in most MIR limited materials.…”

Section: Dmentioning

confidence: 97%

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High-temperature resistivity in the iron pnictides and the electron-doped cuprates

et al. 2011

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We measured the high temperature (up to 800 K) resistivity of several dopings of SrFe2−x(Ni,Co)xAs2 (122) and compared the results with similar measurements on electron-doped cuprates. We find that the Sr-122 pnictide resistivity saturates above 500 K at around 400 − 700 µΩ·cm, consistent with the Mott-Ioffe-Regel (MIR) limit and in contrast to the MIR violating behavior of the hole-doped cuprates and our measurements on electrondoped cuprates. This supports the view that electronic correlations in the ferropnictides may be weaker than in the cuprates.

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Section: Discussioncontrasting

confidence: 55%

Section: Introductionmentioning

confidence: 75%

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High-temperature resistivity in the iron pnictides and the electron-doped cuprates

et al. 2011

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“…LnFeAsO 1−δ oxygen deficient (optimally doped at δ=0.15) with no fluorine doping obtained by high pressure synthesis has been reported to be a superconductor 33 ; this process is similar to the well known oxygenation of the cuprates. It is worthwhile to mention that a maximum superconducting temperature transition around 47 K has been reported previously for optimally doped samples synthesized by normal pressure solid state chemical reaction 29,34 , while a slightly enhanced T C of 52 K was reported for the samples synthesized using a high pressure method …”

Section: Resultsmentioning

confidence: 63%

Phase diagram of thePrFeAsO1−xFxsuperconductor

et al. 2009

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The electronic phase diagram of PrFeAsO1−xFx (0≤x≤0.225) has been determined using synchrotron X-ray powder diffraction, magnetization and resistivity measurements. The structural transition temperature is suppressed from 154 K to ≈120 K and the magnetic phase transitions of both iron and praseodymium ions are completely suppressed by x≈0.08 fluorine doping, coinciding with the emergence of superconductivity. The optimal doping is x≈0.15 when TC =47 K, while the maximum solubility of fluorine in PrFeAsO1−xFx is reached around x=0.22. The structural, magnetic and superconducting phase diagram is presented.

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“…underestimates H c2 in two-band superconductors [19], huge upper critical fields are expected in these compounds. More certain evaluations will require magneto-resistivity measurements at much higher applied magnetic field.…”

Section: Resultsmentioning

confidence: 96%

Physical property characterization of single step synthesized NdFeAsO0.80F0.20 bulk 50 K superconductor

et al. 2010

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We report an easy single step synthesis route of title compound Although by now nearly two years are over after the discovery of superconductivity in C. Finally the sample was allowed to cool down to room temperature. All the heating schedules were given in one single step. The resultant compound was hard enough for transport measurements and was black in color. Typically, 1 gram of raw pellet was sealed in 2.5 cm diameter and 10 cm length high quality "thick walled" quartz tube. The X-ray diffraction pattern of the compound was taken on a Rigaku diffractometer using CuK α radiation and the Rietveld analysis was carried out to know the lattice parameters and impurities etc., if present at all. Magneto-resistivity measurement R(T)H up to 14 T Field and DC magnetic susceptibility in both zero-field-cooled (zfc) and field-cooled (fc) situations along with the isothermal magnetization (MH) measurements were carried out on a physical property measurement system (PPMS) from Quantum Design (QD). The AC susceptibility at different frequencies (33 to 9999 Hz) & different amplitudes (1 to 15 Oe) of AC drive field with 4 temperatures down to 5 K, the specific heat with temperature down to 2.2 K and thermo-electric power (TEP) were also measured on the same physical property measurement system (PPMS). Figure The upper critical field is determined using different criterion of H c2 =H at which =90% N or 50% N or 10% N , where  N is the normal resistivity or resistance at about 51 K. RESULTS AND DISCUSSIONThe H c2 variation with temperature is shown in Figure 2(c). To determine H c2 (0) value, we applied Ginzburg Landau (GL) theory. The GL equation is:Where, t=T/T c is the reduced temperature [18]. DC magnetic susceptibility versus temperature plot in both zero-field-cooled (zfc) and field-cooled (fc) situations is given in Figure 3. The applied magnetic field is 50 Oe.Superconductivity sets in below 49 K, as evidenced from clear diamagnetic signal at this temperature. Although the transition seems slightly broad the same is still sharper than previous reports on polycrystalline NdFeAsO/F [14,15]. Both zfc and fc are nearly saturated below 30 K.As far as the determination of superconducting volume fraction is concerned the same cannot be ascertained without ambiguity primarily due to positive paramagnetic contribution to magnetic susceptibility from Nd/Fe moments and secondly the pinning defects and impurities hamper the real outcome. Still one can say with confidence that the studied compound is a bulk superconductor with shielding fraction above 25% and superconducting volume fraction of > 8%. 7Measurement of the AC susceptibility can be conveniently used to investigate both intergrain and intragrain vortex dynamics in superconductors [31][32][33]. Figure sample is a granular superconductor like other reported oxy-pnictides.The temperature variation of the AC susceptibility measured at different AC field amplitudes 1, 2, 4, 6, 8, 10, 12, 13 & 15 Oe is shown in Figure 5. The diamagnetic onset temperature is ~ 47.7 K...

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Resistivity saturation in PrFeAsO_1−xF_ysuperconductor: evidence of strong electron–phonon coupling

Cited by 30 publications

References 39 publications

High-temperature resistivity in the iron pnictides and the electron-doped cuprates

High-temperature resistivity in the iron pnictides and the electron-doped cuprates

Phase diagram of thePrFeAsO1−xFxsuperconductor

Physical property characterization of single step synthesized NdFeAsO0.80F0.20 bulk 50 K superconductor

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