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Pinterić, Marko; Tomić, Silvia; Prester, M.; Drobac, Đuro; Milat, Ognjen; Maki, Kazumi; Schweitzer, Dieter; Heinen, I.; Strunz, W.

doi:10.1103/physrevb.61.7033

Cited by 60 publications

(68 citation statements)

References 44 publications

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“…We observe upward curvature of ρ s (T ) in this vicinity, consistent with the superfluid density becoming frequency dependent as the sample enters the vortex-plasma regime, an effect that is prominent in cuprates. 60,61 A similar analysis carried out on previously published data, [26][27][28][29][47][48][49][50] in which ρ s (T ) is 4 to 40 times smaller, predicts vortex unbinding in the range 3 to 8 K. This is not observed. Finally, our data have recently been shown to be consistent 62 with the Homes scaling law 63 relating superfluid density to the product of normal-state conductivity and T c .…”

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In-plane superfluid density and microwave conductivity of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence for
Milbradt
¹
,
Bardin
²
,
Truncik
³

et al. 2013
Phys. Rev. B
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We report the in-plane microwave surface impedance of a high-quality single crystal of κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Br. In the superconducting state, we find three independent signatures of d-wave pairing: (i) a strong, linear temperature dependence of superfluid density; (ii) deep in the superconducting state the quasiparticle scattering rate ∼ T 3 ; and (iii) no BCS coherence peak is observed in the quasiparticle conductivity. Above T c , the Kadowaki-Woods ratio and the temperature dependence of the in-plane conductivity show that the normal state is a Fermi liquid below 23 K, yet resilient quasiparticles dominate the transport up to 50 K. It has been widely argued that the doped Mott insulator describes the essential physics of the cuprates.1 Similarly, the physics of the κ-(ET) 2 X salts (ET is an abbreviation of BEDT-TTF) appears to be connected to the bandwidth-controlled Mott transition.2 Thus, it is essential to identify and understand the important similarities and differences between these two classes of quasi-two-dimensional superconductor. In both the cuprates and the κ-(ET) 2 X salts, the superconducting critical temperature is only two orders of magnitude smaller than the Fermi temperature; in this sense, both are high-temperature superconductors.A broad consensus that the cuprates are d-wave superconductors was quickly reached.3-6 However, the nature of the pairing state of the κ-(ET) 2 X salts has taken longer to understand due to the lack of a "smoking gun" experiment. 7,8 Early on there was clear evidence for singlet pairing. [9][10][11][12] This, and the low symmetry of the organics, limits the pairing symmetry to be either s-wave (A 1g representation of the D 2h point group) or d-wave (B 2g ).13 Early heat capacity experiments suggested s-wave pairing, 14,15 but more recent low-temperature data point to d-wave pairing. 16 Measurements of the NMR relaxation rate support unconventional pairing. [9][10][11][12] Disorder studies show a reduction in T c with increasing scattering 17,18 but, for larger scattering rates, the suppression of T c is less than expected for non-s-wave superconductors.Attempts to locate the nodes expected in a d-wave superconductor have not yet yielded a simple picture. The in-plane thermal conductivity shows a fourfold angular variation with minima at 45• to the crystal axes, 19 whereas when a magnetic field is rotated in the plane both the heat capacity 20 and the millimeter wave absorption 21 have minima when the field is aligned with the crystal axes. At first sight these results seem contradictory, but both experiments are extremely difficult to interpret 22 and a complicated phase diagram could occur as a function of field strength and temperature. 20,22 Nevertheless, as this has not yet been observed, these measurements have not yet settled the pairing symmetry. There have also been attempts to directly image the gap via scanning tunneling microscopy (STM).23 Some care is needed with the interpretation of these experiments as the coherence peaks, the key feature of ...

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confidence: 55%

“…[26][27][28][29][47][48][49][50] Since this amounts to a substantial revision, it is critical that we check its validity. The principle measurement uncertainties in λ arise from the surface impedance scale factor and the normal-state matching technique used to determine absolute reactance.…”

mentioning

confidence: 99%

In-plane superfluid density and microwave conductivity of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence for
Milbradt
¹
,
Bardin
²
,
Truncik
³

et al. 2013
Phys. Rev. B
35
4
46
1
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“…This suggests strongly the universality of d-wave superconductivity for all high-T c cuprate superconductors. Further, recent measurements of the magnetic penetration depth in organic superconductor κ-(BEDT-TTF) 2 Cu(N(CN) 2 )Br indicates this system has also dwave superconductivity, 4,5 though the phase sensitive experiment is not available for this system. Also uncertain is the nodal directions of the order parameter 6,7 in κ-(ET) 2 salts in spite of the theoretical suggestion that it belongs to d xy -symmetry.…”

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confidence: 99%

Quasi-particle transport in vortex state of nodal superconductors

Won

Maki

2001

Current Applied Physics

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Quasiparticle spectrum associated with the nodal structure in d-wave superconductors is of great interest. We study theoretically the quasi-particle spectrum in a planar magnetic field, where the effect of the magnetic field is treated in terms of the Doppler shift. We obtain the angular dependent specific heat in the presence of a planar magnetic field and impurities, both in the superclean limit(≪ 1) and in the clean limit(. Also a similar analysis is used for the thermal conductivity tensor within the a-b plane. In particular, in contrast to the earlier works, we find a fourfold symmetry term in κ and κ ⊥ ∼ −H sin(2θ) where κ and κ ⊥ are the diagonal-and the off-diagonal components of the thermal conductivity tensor and θ is the angle between the heat current and the magnetic field.

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“…-Now d x 2 −y 2 -wave superconductivity is well established in both holedoped and electron-doped high temperature cuprate superconductors [1][2][3][4][5]. Further superconductivity in organic conductors in κ − (ET ) 2 salts appears to be of d-wave [6,7]. In spite of these developments, the optical conductivity in d-wave superconductors appears to be not well understood.…”

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confidence: 99%

Optical conductivity of the p-wave superconductor Sr2RuO4

Dóra

Virosztek

Maki

2000

Physica C: Superconductivity

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PACS. 74.20.-z -Theories and models of superconducting states. PACS. 74.25.Fy -Transport properties. PACS. 74.25.Gz -Optical properties.Abstract. -We study theoretically the optical conductivity of d-wave superconductors like in high temperature cuprates in the presence of impurities. We limit ourselves at T = 0K and focus on the frequency dependence of both σ1(ω) and ωσ2(ω) for ω 2∆. When the impurity scattering is in the unitary limit, we find a peak in σ1(ω) with ω/∆ ≃ 0.1 ∼ 0.5, which may account for the peak seen by Basov et al. in Zn-substituted Y BCO.Introduction. -Now d x 2 −y 2 -wave superconductivity is well established in both holedoped and electron-doped high temperature cuprate superconductors [1][2][3][4][5]. Further superconductivity in organic conductors in κ − (ET ) 2 salts appears to be of d-wave [6,7]. In spite of these developments, the optical conductivity in d-wave superconductors appears to be not well understood. For example Hirschfeld et al. [8] considered the microwave conductivity in d-wave superconductors in the presence of impurity in the unitary limit. However they were more interested in the temperature dependence rather than the frequency dependence. Similarly Sun and Maki [9] and Graf et al.[10] studied only some aspect of the optical conductivity. On the other hand, a recent infrared conductivity in Zn-substituted Y BCO exhibits a peak around ω/∆ ≃ 0.1 ∼ 0.2, which cannot be accounted for the above theories [11]. The object of this paper is to study the in plane optical conductivity focusing on the frequency dependence at T = 0K. As a model we take d-wave superconductors (with gap function ∆(k) = ∆ cos(2φ), φ is the in plane angle measured from the k x direction) in the presence of impurities in the unitary and Born limit. We assume that the former describes the Zn impurity while the latter the N i impurity [12]. In the following we summarize what we needed for the model, then we calculate σ 1 (ω) and ωσ 2 (ω) for impurities in the unitary and the Born limit for several impurity concentrations. Indeed, for the impurity in the unitary limit σ 1 (ω) develops a peak around ω/∆ ≃ 0.1 ∼ 0.2, somewhat similar to the one observed in Zn-substituted Y BCO. On the other hand, σ 1 (ω) in the Born limit develops a broad bump around ω/∆ ∼ 1.5.

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Probing the order parameter of the layered organic superconductorκ−(BEDT−TTF

Cited by 60 publications

References 44 publications

In-plane superfluid density and microwave conductivity of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence for
Milbradt
¹
,
Bardin
²
,
Truncik
³

et al. 2013
Phys. Rev. B
35
4
46
1
View full text Add to dashboard Cite

In-plane superfluid density and microwave conductivity of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence for
Milbradt
¹
,
Bardin
²
,
Truncik
³

et al. 2013
Phys. Rev. B
35
4
46
1
View full text Add to dashboard Cite

Quasi-particle transport in vortex state of nodal superconductors

Optical conductivity of the p-wave superconductor Sr2RuO4

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Probing the order parameter of the layered organic superconductorκ−(BEDT−TTF

Cited by 60 publications

References 44 publications

In-plane superfluid density and microwave conductivity of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence forMilbradt1, Bardin2, Truncik3 et al. 2013Phys. Rev. B354461View full textAdd to dashboardCite

In-plane superfluid density and microwave conductivity of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence forMilbradt1, Bardin2, Truncik3 et al. 2013Phys. Rev. B354461View full textAdd to dashboardCite

Quasi-particle transport in vortex state of nodal superconductors

Optical conductivity of the p-wave superconductor Sr2RuO4

Contact Info

Product

Resources

About

In-plane superfluid density and microwave conductivity of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence for
Milbradt
¹
,
Bardin
²
,
Truncik
³

et al. 2013
Phys. Rev. B
35
4
46
1
View full text Add to dashboard Cite

In-plane superfluid density and microwave conductivity of the organic superconductorκ-(BEDT-TTF)2Cu[N(CN)2]Br: Evidence for
Milbradt
¹
,
Bardin
²
,
Truncik
³

et al. 2013
Phys. Rev. B
35
4
46
1
View full text Add to dashboard Cite