Large decrease in the critical temperature of superconducting<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>LaFeAsO</mml:mtext></mml:mrow><mml:mrow><mml:mn>0.85</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>compounds doped with 3% atomic weight of nonmagnetic Zn impurities

Guo, Yanfeng; Shi, Youguo; Yu, S.; Belik, Alexei А.; Matsushita, Yoshitaka; Tanaka, Masashi; Katsuya, Yoshio; Kobayashi, Keisuke; Nowik, I.; Felner, I.; Awana, V. P. S.; Yamaura, Kazunari; Takayama‐Muromachi, E.

doi:10.1103/physrevb.82.054506

Cited by 64 publications

(61 citation statements)

References 56 publications

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“…The behaviors of T c suppression by impurity doping in both RFeAs(O,F) and LaFeP(O,F) are very similar, i.e., the magnetic impurity of Mn strongly reduces T c , while the nonmagnetic impurities do not largely destabilize the SC state [29][30][31][32]. The previous and present experimental results may have indicated that these effects of destabilization of superconductivity by magnetic and nonmagnetic impurities are a common feature in iron-based SC materials.…”

Section: Discussionsupporting

confidence: 62%

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

2016

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Abstract:We have investigated Mn, Co and Ni substitution effects on polycrystalline samples of LaFePO 0.95 F 0.05 by resistivity and magnetoresistance measurements. In LaFe 1-x M x PO 0.95 F 0.05 (M = Mn, Co and Ni), the superconducting transition temperature (T c ) monotonously decreases with increasing the impurity doping level of x. There is a clear difference of T c suppression rates among Mn, Co and Ni doping cases, and the decreasing rate of T c by Mn doping as a magnetic impurity is larger than those by the nonmagnetic doping impurities (Co/Ni). This result indicates that in LaFePO 0.95 F 0.05 , T c is rapidly suppressed by the pair-breaking effect of magnetic impurities, and the pairing symmetry is a full-gapped s-wave. In the nonmagnetic impurity-doped systems, the residual resistivity in the normal state has nearly the same value when T c becomes zero. The residual resistivity value is almost consistent with the universal value of sheet resistance for two-dimensional superconductors, suggesting that T c is suppressed by electron localization in Co/Ni-doped LaFePO 0.95 F 0.05 .

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Section: Discussionsupporting

confidence: 62%

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

2016

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“…In The anisotropic lattice feature is remarkably contrast with what was found for LaFeAsO 1-δ [26] and TbFeAsO 1-δ [27], in which the unit cell is isotropically contracted with increasing amount of the oxygen vacancies. Nevertheless, the systematic lattice change is indicative of successful doping of the oxygen vacancies into the structure, although we were unable to measure the net oxygen concentration by a chemical method because of the toxic effects.…”

Section: Results and Discusionmentioning

confidence: 62%

“…We thus focused on a specific Fe-based compound that has increasing distance between the layers, as was successful in the oxyarsenides such as LaFeAsO 1-δ [26] and TbFeAsO 1-δ [27].…”

Section: Introductionmentioning

confidence: 99%

Magnetic and electrical properties and carrier doping effects on the iron-based host compound Sr2ScFeAsO3

et al. 2011

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Additional charge carriers were introduced to the iron oxyarsenide Sr 4 Sc 2 Fe 2 As 2 O 6 under a high-pressure condition, followed by measurements of electrical resistivity, Hall coefficient, and magnetic susceptibility. The host compound Sr 4 Sc 2 Fe 2 As 2 O 6 shows metallic conductivity down to ~200 K and turns to show a semiconducting-like conductivity accompanied by a positive magneto-resistance (22% at 70 kOe). Although the carrier density is comparable at 300 K (5.9×10 21 cm -3 ) with that of the other Fe-based superconductors, no superconductivity appears down to 2 K. This is primarily because the net carrier density decreases over 3 orders of magnitude on cooling and additionally a possible magnetic order at ~120 K prevents carriers from pairing. The properties were altered largely by introducing the additional carriers.

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“…The effect of the metal-insulator transition on T c is also known for Cu oxides. [22][23][24] Rather strong T c -suppression observed for Zn doped samples prepared under high pressure 25) can also be understood by this effect. In this case, to remove the effects of grain boundaries, we use a factor 1/2 smaller than the value 1/4 used above, considering the high pressure preparation of the samples and easily find that the critical resistivity for zero T c roughly corresponds to the sheet resistance of 6.45 k .…”

Section: -11)mentioning

confidence: 87%

On the Magnetic Excitation Spectra of Ba(Fe_0.9Co_0.1)₂As₂in the Superconducting State

et al. 2011

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Magnetic excitation spectra of Ba(Fe 0.9 Co 0.1 ) 2 As 2 obtained for aligned crystals with the superconducting transition temperature T c 23 K are presented after an overview of results of our preceding studies on the symmetry of the order parameter . Although many researchers have reported that their experimental results are consistently explained by the so-called S symmetry, and believe that the spin-fluctuation is relevant to the superconducting mechanism of Fe pnictide superconductors. However, the situation is not so simple, because almost all these data can be understood by the S ++ -symmetry, too. Furthermore, as we first pointed out and discussed in detail, the rates of the T c suppression by nonmagnetic impurities can hardly be explained by the S symmetry. Here, we show our own data of the magnetic excitation spectra of Ba(Fe 0.9 Co 0.1 ) 2 As 2 , and discuss which one of the S and S ++ -symmetries can better describe the characteristics of the peak observed there. These processes are important, because the S and S ++ symmetries are connected with the spin-fluctuation mechanism and a newly proposed one related to the orbital degrees of freedom of the systems, respectively.

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Large decrease in the critical temperature of superconductingLaFeAsO0.85compounds doped with 3% atomic weight of nonmagnetic Zn impurities

Cited by 64 publications

References 56 publications

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

Magnetic and electrical properties and carrier doping effects on the iron-based host compound Sr2ScFeAsO3

On the Magnetic Excitation Spectra of Ba(Fe_0.9Co_0.1)₂As₂in the Superconducting State

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Large decrease in the critical temperature of superconductingLaFeAsO0.85compounds doped with 3% atomic weight of nonmagnetic Zn impurities

Cited by 64 publications

References 56 publications

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

Superconducting Gap Symmetry of LaFeP(O,F) Observed by Impurity Doping Effect

Magnetic and electrical properties and carrier doping effects on the iron-based host compound Sr2ScFeAsO3

On the Magnetic Excitation Spectra of Ba(Fe0.9Co0.1)2As2in the Superconducting State

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On the Magnetic Excitation Spectra of Ba(Fe_0.9Co_0.1)₂As₂in the Superconducting State