Effects of cobalt doping and phase diagrams of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>L</mml:mi><mml:msub><mml:mrow><mml:mtext>Fe</mml:mtext></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mrow><mml:mtext>Co</mml:mtext></mml:mrow><mml:mi>x</mml:mi></mml:msub><mml:mtext>AsO</mml:mtext></mml:mrow></mml:math>(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mm

Wang, Cao; Li, Y K; Zhu, Zengwei; Jiang, Shuai; Lin, Xin; Luo, Yongkang; Chi, Shun; Li, L J; Ren, Zhi; He, Meng; Chen, H; Wang, Y T; Qian, Tao; Cao, Guang‐Han; Xu, Z. A.

doi:10.1103/physrevb.79.054521

Cited by 188 publications

(152 citation statements)

References 41 publications

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“…2. The a axis is almost constant at low doping levels, in agreement with other cobalt-doped superconductors, 17,39 and increases moderately for x Ͼ 0.25.…”

Section: Structure and Properties Of Ndfe 1−x Cosupporting

confidence: 69%

“…The presence of a "dome" and possible overlap between magnetic and SC regions is consistent with results published for other 1111-and 122-type cobalt-doped superconductors although the existence of phase coexistence is still under debate. 9,17,18,45 The critical field, H c2 ͑T͒, increases by approximately 2.3͑1͒ T K −1 for the three measured compositions upon cooling below T c . This is smaller than for "indirect" ͑not Fe-site͒ electron-doped superconductors, such as NdFeAsO 1−x F x , where values of 4 -5 T K −1 have been observed.…”

Section: Discussionmentioning

confidence: 99%

“…By contrast in the iron arsenides, direct substitution on the Fe site with a variety of transition metals is known to induce superconductivity. This was first reported for 1111-type LaFe 1−x Co x AsO with a maximum critical temperature of 13-14 K. 13 Other wellcharacterized cobalt-doped superconductors include 122-type AE͑Fe 1−x Co x ͒ 2 As 2 ͑AE = Ba, Sr, and Ca͒, [14][15][16] 1111-type SmFe 1−x Co x AsO, 17 and 1111-type CaFe 1−x Co x AsF. 18 The highest reported T c for cobalt doping is 22 K and is found for Ba͑Fe 1−x Co x ͒ 2 As 2 and CaFe 1−x Co x AsF.…”

Section: Introductionmentioning

confidence: 99%

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Superconductivity inNdFe1−xCoxAsO(

et al. 2010

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The phase diagram of NdFe 1−x Co x AsO for low cobalt substitution consists of a superconducting dome ͑0.05Ͻ x Ͻ 0.20͒ with a maximum critical temperature of 16.5͑2͒ K for x = 0.12. The x = 1 end member, NdCoAsO, is an itinerant ferromagnet ͑T C =85 K͒ with an ordered moment of 0.30͑1͒ B at 15 K. Below T N = 9 K, Nd spin ordering results in the antiferromagnetic coupling of the existing ferromagnetic planes. Rietveld analysis reveals that the electronically important twofold tetrahedral angle increases from 111.4°to 115.7°in this series. Underdoped samples with x = 0.046͑2͒ and x = 0.065͑2͒ show distortions to the orthorhombic Cmma structure at 72͑2͒ and 64͑2͒ K, respectively. The temperature dependences of the critical fields H c2 ͑T͒ near T c are linear with almost identical slopes of 2.3͑1͒ T K −1 for x = 0.065͑2͒, x = 0.118͑2͒, and x = 0.172͑2͒. The estimated critical field H c2 ͑0͒ and correlation length for optimally doped samples are 26͑1͒ T and 36͑1͒ Å. A comparison of the maximum reported critical temperatures of well-characterized cobalt-doped 122-and 1111-type superconductors is presented.

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“…2. The a axis is almost constant at low doping levels, in agreement with other cobalt-doped superconductors, 17,39 and increases moderately for x Ͼ 0.25.…”

Section: Structure and Properties Of Ndfe 1−x Cosupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Superconductivity inNdFe1−xCoxAsO(

et al. 2010

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“…In addition, d Fe-Fe values are decreased by Co-co-doping with 0.01-0.02 Å compared to TM-free samples. This result is similar to the decrease in c-axis length by Co doping in LaFeAsO [15] and CaFeAsH [16] , indicating that Co-co-doping also accompanies electron doping in (Ca,RE)112. Further careful studies are needed to clarify the reason of relatively high T c by direct TM doping to Fe site which increases electron carrier in already electron overdoped (Ca,RE)112 [11] .…”

Section: Resultssupporting

confidence: 74%

Dependences on RE of superconducting properties of transition metal co-doped (Ca,RE)FeAs2 with RE= La–Gd

Yakita

Sala

Okada

et al. 2015

Physica C: Superconductivity and its Applications

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Dependence of superconducting properties of (Ca,RE)(Fe,TM)As 2 [(Ca,RE)112, TM: Co, Ni)] on RE elements (RE = La-Gd) was systematically investigated. Improvement of superconducting properties by Co or Ni co-doping was observed for all (Ca,RE)112, which is similar to Co-co-doped (Ca,La)112 or (Ca,Pr)112. T c of Co-co-doped samples decreased from 38 K for RE = La to 29 K for RE = Gd with decreasing ionic radii of RE 3+ . However, Co-co-doped (Ca,Eu)112 showed exceptionally low T c = 21 K probably due to the co-existence of Eu 3+ and Eu 2+ suggested by longer interlayer distance d Fe-Fe of (Ca,Eu)112 than other (Ca,RE)112.

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“…14,19 For the case of RE = Sm and Nd, both show behavior similar to the Ce compounds on the Fe-rich side. 14,20,21 However, on the Coend, namely, SmCoAsO and NdCoAsO, complex magnetic properties were observed, in which the Co moments sequentially undergo an FM and an AFM transition, followed by an AFM transition of 4f electrons at T Sm N = 5 K and T Nd N = 3.5 K. 22,23 By applying a magnetic field, such an FM-AFM transition quickly shifts to lower temperatures, showing a large magnetoresistance effect up to the Curie temperature. 24 However, in GdCoAsO, the magnetic susceptibility exhibits a broad maximum at temperatures below T Co C , being different from the FM-AFM transition in the Sm-and Nd-case, and its origin remains unclear.…”

Section: Introductionmentioning

confidence: 99%