Synthesis of a new alkali metal–organic solvent intercalated iron selenide superconductor with<i>T</i><sub>c</sub>≈ 45 K

Krztoń‐Maziopa, A.; Pomjakushina, E.; Pomjakushin, Vladimir; Rohr, Fabian von; Schilling, Andreas; Conder, K.

doi:10.1088/0953-8984/24/38/382202

Cited by 119 publications

(131 citation statements)

References 41 publications

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“…T c 's of the FeSe-based superconductors obtained so far at ambient pressure are summarized in Fig. 6 as a function of d. 1,7,8,10,11,[13][14][15]17,19,20,[23][24][25][26][27] As for the origin of the decrease in T c at d > 9 Å, it may be due to the decrease of the interlayer coupling of cooper pairs. Considering the superconductivity above 100 K in single-layer FeSe films as mentioned above, 6) however, this may be incorrect.…”

Section: (B) and (C)mentioning

confidence: 99%

New Superconducting Phase of Li_x(C₆H₁₆N₂)_yFe₂₋_zSe₂ with T_c = 41 K Obtained through the Post-Annealing

et al. 2016

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Section: (B) and (C)mentioning

confidence: 99%

New Superconducting Phase of Li_x(C₆H₁₆N₂)_yFe₂₋_zSe₂ with T_c = 41 K Obtained through the Post-Annealing

et al. 2016

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“…In an effort to investigate this latter effect, organic molecular complexes including alkalis were recently intercalated between the FeSe layers [12][13][14][15][16][17][18][19] 15 . The crystal structure of a stoichiometric version of these materials is shown in Fig.…”

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confidence: 99%

Unified picture of the doping dependence of superconducting transition temperatures in alkali metal/ammonia intercalated FeSe

et al. 2015

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In the recently synthesized Lix(NH2)y(NH3)zFe2Se2 family of iron chalcogenides a molecular spacer consisting of lithium ions, lithium amide and ammonia separates layers of FeSe. It has been shown that upon variation of the chemical composition of the spacer layer, superconducting transition temperatures can reach Tc ∼ 44 K, but the relative importance of the layer separation and effective doping to the Tc enhancement is currently unclear. Using state of the art band structure unfolding techniques, we construct eight-orbital models from ab-initio density functional theory calculations for these materials. Within an RPA spin-fluctuation approach, we show that the electron doping enhances the superconducting pairing, which is of s±-symmetry and explain the experimentally observed limit to Tc in the molecular spacer intercalated FeSe class of materials.PACS numbers: 71.15. Mb, 71.18.+y, 74.20.Pq, 74.24.Ha, 74.70.Xa After the discovery of iron based superconductors in 2008, transition temperatures were quickly improved to ∼ 56 K by chemical substitution 1 . Recently, the possible discovery of superconductivity with T c = 65 K 2 and even T c ∼ 100 K 3 in single-layer FeSe films grown by molecular beam epitaxy on SrTiO 3 showed that temperatures close to and above the boiling point of liquid nitrogen (77 K) might be achievable. These results have initiated an intensive debate regarding the origin of the high superconducting temperatures and the role played by electron doping via substrate, dimensionality and lattice strain.While bulk FeSe has a T c of only 8-10 K, it has been known for some time that it can be substantially enhanced, to 40 K or higher by alkali intercalation 4 . Materials with a single alkali A = K, Cs, Rb between FeSe layers of nominal form A x Fe 2−y Se 2 have been intensively studied, and shown to display a wide variety of unusual behaviors relative to the Fe pnictide superconducting materials 5 . These include likely phase separation into an insulating phase with block antiferromagnetism and ordered Fe vacancies, and a superconducting phase that is strongly alkali deficient and whose Fermi surface as measured by ARPES apparently contains no holelike Fermi surface pockets, in contrast to Fe-pnictides. Since the popular spin fluctuation scenario for s ± pairing relies on near nesting of hole and electron pockets, it has been speculated that a different mechanism for pairing might be present in these materials, and even within the spin fluctuation approach, different gap symmetries including d-wave pairing have been proposed 6-9 . The gap symmetry and structure is still controversial, however 10,11 .In addition to the unusual doping, speculation on the origin of the higher T c has centered on the intriguing possibility that enhancing the FeSe layer spacing improves the two-dimensionality of the band structure and hence Fermi surface nesting 12,13 . In an effort to investigate this latter effect, organic molecular complexes including alkalis were recently intercalated between the FeSe layers 12-19 ,...

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“…This is in contrast to the FeSe superconductor which is a layered quasi-2D solid, composed of electronically neutral planes analogous to graphite. Successful attempts at achieving tunability in the FeSe system include-besides pressure-neutral molecular intercalants as well as alkali metal organic [26] and molecular [27]. Attempts at merging of graphene with FeSe were made previously.…”

Section: Resultsmentioning

confidence: 99%

Enhanced Manifold of States Achieved in Heterostructures of Iron Selenide and Boron-Doped Graphene

Cantatore

Panas

2017

Condensed Matter

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Enhanced superconductivity is sought by employing heterostructures composed of boron-doped graphene and iron selenide. Build-up of a composite manifold of near-degenerate noninteracting states formed by coupling top-of-valence-band states of FeSe to bottom-of-conductionband states of boron-doped graphene is demonstrated. Intra-and intersubsystem excitons are explored by means of density functional theory in order to articulate a normal state from which superconductivity may emerge. The results are discussed in the context of electron correlation in general and multi-band superconductivity in particular.

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Synthesis of a new alkali metal–organic solvent intercalated iron selenide superconductor withT_c≈ 45 K

Cited by 119 publications

References 41 publications

New Superconducting Phase of Li_x(C₆H₁₆N₂)_yFe₂₋_zSe₂ with T_c = 41 K Obtained through the Post-Annealing

New Superconducting Phase of Li_x(C₆H₁₆N₂)_yFe₂₋_zSe₂ with T_c = 41 K Obtained through the Post-Annealing

Unified picture of the doping dependence of superconducting transition temperatures in alkali metal/ammonia intercalated FeSe

Enhanced Manifold of States Achieved in Heterostructures of Iron Selenide and Boron-Doped Graphene

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Synthesis of a new alkali metal–organic solvent intercalated iron selenide superconductor withTc≈ 45 K

Cited by 119 publications

References 41 publications

New Superconducting Phase of Lix(C6H16N2)yFe2−zSe2 with Tc = 41 K Obtained through the Post-Annealing

New Superconducting Phase of Lix(C6H16N2)yFe2−zSe2 with Tc = 41 K Obtained through the Post-Annealing

Unified picture of the doping dependence of superconducting transition temperatures in alkali metal/ammonia intercalated FeSe

Enhanced Manifold of States Achieved in Heterostructures of Iron Selenide and Boron-Doped Graphene

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Synthesis of a new alkali metal–organic solvent intercalated iron selenide superconductor withT_c≈ 45 K

New Superconducting Phase of Li_x(C₆H₁₆N₂)_yFe₂₋_zSe₂ with T_c = 41 K Obtained through the Post-Annealing

New Superconducting Phase of Li_x(C₆H₁₆N₂)_yFe₂₋_zSe₂ with T_c = 41 K Obtained through the Post-Annealing