Scanning Tunneling Spectroscopy on κ-(BEDT-TTF)2Cu[N(CN)2]Br

Ichimura, Kunihiro; Higashi, Saburo; Nomura, K.; Kawamoto, Atsushi

doi:10.1016/j.synthmet.2005.07.318

Cited by 14 publications

(13 citation statements)

References 27 publications

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“…In contrast to early specific heat measurements that supported swave pairing 88,89 , more recent measurements are consistent with a nodal order parameter 90 . Microwave penetration depth measurements 91,92 as well as STM tunneling experiments [93][94][95][96][97][98] are also consistent with nodes.…”

Section: Symmetry Of Superconducting Order Parametersupporting

confidence: 70%

Coulomb enhancement of superconducting pair-pair correlations in a34-filled model forκ−(BEDT-TTF)2X

Silva¹,

Gomes²,

Mazumdar³

et al. 2016

Phys. Rev. B

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We present the results of precise correlated-electron calculations on the monomer lattices of the organic charge-transfer solids κ-(BEDT-TTF)2X for 32 and 64 molecular sites. Our calculations are for band parameters corresponding to X = Cu[N(CN)2]Cl and Cu2(CN)3, which are semiconducting antiferromagnetic and quantum spin liquid, respectively, at ambient pressure. We have performed our calculations for variable electron densities ρ per BEDT-TTF molecule, with ρ ranging from 1 to 2. We find that d-wave superconducting pair-pair correlations are enhanced by electron-electron interactions only for a narrow carrier concentration about ρ = 1.5, which is precisely the carrier concentration where superconductivity in the charge-transfer solids occurs. Our results indicate that the enhancement in pair-pair correlations is not related to antiferromagnetic order, but to a proximate hidden spin-singlet state that manifests itself as a charge-ordered state in other chargetransfer solids. Long-range superconducting order does not appear to be present in the purely electronic model, suggesting that electron-phonon interactions also must play a role in a complete theory of superconductivity.

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Section: Symmetry Of Superconducting Order Parametersupporting

confidence: 70%

Coulomb enhancement of superconducting pair-pair correlations in a34-filled model forκ−(BEDT-TTF)2X

Silva¹,

Gomes²,

Mazumdar³

et al. 2016

Phys. Rev. B

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“…For example, the zero-bias conductance peak (ZBCP) in the tunneling spectrum of high T c superconductors [4][5][6] has been ascribed to the zero-energy bound states. ZBCP has been also observed in other superconductors, such as Sr 2 RuO 4 , 7) -(BEDT-TTF) 2 Cu[N(CN) 2 ]Br, 8) UBe 13 , 9) and CeCoIn 5 , 10) and was regarded as evidence of their unconventionality. The surface bound states in p-wave pairing superfluid 3 He 1,2,11-13) have not been observed until recently, because of the lack of an appropriate probe for the neutral superfluid.…”

mentioning

confidence: 85%

Strong Anisotropy in Spin Susceptibility of Superfluid³He-B Film Caused by Surface Bound States

2009

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Spin susceptibility of superfluid 3 He-B film with specular surfaces is calculated on the basis of the self consistent order parameter. It is shown that, when the magnetic field is applied in a direction perpendicular to the film, the suseptibility is significantly enhanced by the contribution from the surface bound states. No such enhancement is found for the magnetic field parallel to the film. A simplified model with spatially constant order parameter is used to elucidate the magnetic properties of the surface bound states. The Majorana nature of the zero energy bound state is also mentioned.

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“…For -(ET)2Cu[N(CN)2]Br (-Br for short): measurements of scanning tunnel spectroscopy (STS) were interpreted as strongly supporting d-wave pairing with line nodes (Ichimura et al [604]); measurements (Mayaffre et al [605]) of NMR 1/T1 ~ T 3 indicate strongly anisotropric superconducting gap or maybe nodes, with no Hebel Schlichter peak in 1/T1 below Tc, i. e. arguing against s-wave; measurements (De Soto et al [606]) of NMR indicate unconventional pairing, possible nodes; measurements (Kanoda et al [607]) of NMR indicate UcS with strong gap anisotropy and possibly nodes; measurements in -Br and -(ET)2Cu(NCS)2 (-NCS for short) (Le et al [608]) of penetration depth ~T consistent with line nodes; measurements (Achkir et al [609]) in -NCS of penetration depth imply line nodes and UcS; measurements (Dressel et al [610]) in -Br and -NCS of surface impedance indicate an anisotropic superconducting gap but without nodes in the gap; measurements (Taylor, Carrington and Schlueter [611]) in -Br and -NCS of the specific heat C~T both indicate d-wave pairing symmetry; measurements (Milbradt et al [612]) in -Br of surface impedance indicate d-wave behavior.…”

Section: Dmentioning

confidence: 99%

Unconventional superconductivity

Stewart

2017

Advances in Physics

221

165

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Abstract:"Conventional" superconductivity, as used in this review, refers to electron-phonon coupled superconducting electron pairs described by BCS theory. Unconventional superconductivity refers to superconductors where the Cooper pairs are not bound together by phonon-exchange but instead by exchange of some other kind, e. g. spin fluctuations in a superconductor with magnetic order either coexistent or nearby in the phase diagram. Such unconventional superconductivity has been known experimentally since heavy fermion CeCu2Si2, with its strongly correlated 4f electrons, was discovered to superconduct below 0.6 K in 1979. Since the discovery of unconventional superconductivity in the layered cuprates in 1986, the study of these materials saw Tc jump to 164 K by 1994. Further progess in high temperature superconductivity would be aided by understanding the cause of such unconventional pairing. This review compares the fundamental properties of 9 unconventional superconducting classes of materialsfrom 4f-electron heavy fermions to organic superconductors to classes where only three known members exist to the cuprates with over 200 examples -with the hope that common features will emerge to help theory explain (and predict!) these phenomena. In addition, three new emerging classes of superconductors (topological, interfacial -e. g. FeSe on SrTiO3, and H2S under high pressure) are briefly covered, even though their "conventionality" is not yet fully determined.

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Scanning Tunneling Spectroscopy on κ-(BEDT-TTF)2Cu[N(CN)2]Br

Cited by 14 publications

References 27 publications

Coulomb enhancement of superconducting pair-pair correlations in a34-filled model forκ−(BEDT-TTF)2X

Coulomb enhancement of superconducting pair-pair correlations in a34-filled model forκ−(BEDT-TTF)2X

Strong Anisotropy in Spin Susceptibility of Superfluid³He-B Film Caused by Surface Bound States

Unconventional superconductivity

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Scanning Tunneling Spectroscopy on κ-(BEDT-TTF)2Cu[N(CN)2]Br

Cited by 14 publications

References 27 publications

Coulomb enhancement of superconducting pair-pair correlations in a34-filled model forκ−(BEDT-TTF)2X

Coulomb enhancement of superconducting pair-pair correlations in a34-filled model forκ−(BEDT-TTF)2X

Strong Anisotropy in Spin Susceptibility of Superfluid3He-B Film Caused by Surface Bound States

Unconventional superconductivity

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Product

Resources

About

Strong Anisotropy in Spin Susceptibility of Superfluid³He-B Film Caused by Surface Bound States