Impurity effects in<i>d</i>-wave superconductors

Sun, Ye; Maki, Kazumi

doi:10.1103/physrevb.51.6059

Cited by 216 publications

(209 citation statements)

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“…Also the deviation from the universal limit in the low temperature thermal conductivity [11] in f-wave superconductor is very similar but somewhat larger than in d-wave superconductor [8], which may be consistent with the recent measurement of electron-irradiated UPt 3 [12].…”

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confidence: 77%

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Impurity scattering in f-wave superconductor UPt3

Yang

Maki

2000

Physica C: Superconductivity

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PACS. 74.20-h -Theory. PACS. 74.25Bt -Thermodynamic properties. PACS. 74.25Fy -Transport properties.Abstract. -We study theoretically the effect of impurity scattering in f-wave (or E2u) superconductors. The quasi-particle density of states of f-wave superconductor is very similar to the one for d-wave superconductor as in hole-doped high Tc cuprates. Also in spite of anisotropy in ∆(k), both the normalized superfluid density and the thermal conductivity is completely isotropic.Introduction. -After a long controversy, f-wave (or E 2u ) superconductivity in UPt 3 is established in 1996 [1]. First the thermal conductivities with the heat current parallel to the c axis and within the basal plane decrease linearly in T the temperature at low temperature [2]. This is consistent with E 2u but inconsistent with the then prevailing model E 1g [3,4]. Almost at the same time 195 Pt Knight shift measurement in UPt 3 finds the spin triplet pair [5]. Later they find also among three phases A, B and C in UPt 3 , only B phase is nonunitary [5]. This is again consistent with E 2u but not with E 1g .So we can write down the superconducting order parameter

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confidence: 77%

“…It is well known that impurity produces profound effect in unconventional superconductors [8,9]. Also for the analysis of transport properties the impurity scattering is crucial.…”

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Impurity scattering in f-wave superconductor UPt3

Yang

Maki

2000

Physica C: Superconductivity

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“…The other is the quasiparticle density of states in the presence of impurities or disorders. Early theoretical work based on self-consistent approximation gave a general conclusion that the impurity scattering generated a residual density of states N(E) at zero quasiparticle energy (Eº0) [10][11][12][13]. Especially, the unitary scattering could lead to a nearly constant N(E) near E=0, which was qualitatively verified by experiments [14][15][16].…”

Section: Pacs: 7425bt; 7425jbmentioning

confidence: 77%

Depression of Quasiparticle Density of States at Zero Energy inLa1.9Sr0.1Cu1−
Chang
¹
,
Lin
²
,
Yang
³

2000
Phys. Rev. Lett.

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We have measured low-temperature specific heat C(T, H) of La 1.9 Sr 0.1 Cu 1-x Zn x O 4 (x=0, 0.01, and 0.02) both in zero and applied magnetic fields. A pronounced dip of C/T below 2 K was first observed in Zn-doped samples, which is absent in the nominally clean one. If the origin of the dip in C/T is electronic, the quasiparticle density of states N(E) in Zn-doped samples may be depressed below a small energy scale E 0 . The present data can be well described by the model N(E)=N(0)+aE 1/2 , with a non-zero N(0) and positive a. N(E) is argued to vanish as E or E 2 depending on whether the time reversal is a good symmetry or not.In principle, the low-temperature specific heat (LTSH) C(T) is a powerful probe of N(E) of the quasiparticle low energy excitation. Nevertheless, previous LTSH experiments in impurity-doped (especially Zn-doped) [14,15,20] cuprates usually suffered a upturn in C/T at low temperatures. This upturn hinders the investigation of the low-temperature electronic contribution in C, and is presumably due to either a hyperfine contribution or the local magnetic moment both of which probably are associated with defects in samples.To shed light on the issue of the low-energy quasiparticle N(E), we have carefully prepared Zn-and Ni-doped La 1.9 Sr 0.1 CuO 4 . These samples show no upturn in C/T down to the lowest experiment temperature 0.6 K. Therefore, LTSH can be readily used to probe N(E) and provide

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“…The dependence of the pair breaking on the imperfect nesting is a very consequence of the interplay between Peierls, Cooper and localization tendencies through the angular dependence of corresponding amplitudes. In the AbrikosovGor'kov theory, [16,17] where particle-hole logarithms are neglected, and a dSC order parameter is phenomenologically assumed, the ratio α * /T α=0 c ≃ 0.88 is independent of nesting.…”

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Effects of Nonmagnetic Impurities on Spin-Fluctuation Induced Superconductivity

Dusuel

Zanchi

2004

Phys. Rev. Lett.

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We study the effects of non-magnetic impurities on the phase diagram of a system of interacting electrons with a flat Fermi surface. The one-loop Wilsonian renormalization group flow of the angle dependent diffusion function D(θ1, θ2, θ3) and interaction U (θ1, θ2, θ3) determines the critical temperature and the nature of the low temperature state. As the imperfect nesting increases the critical temperature decreases and the low temperature phase changes from the spin-density wave (SDW) to the d-wave superconductivity (dSC) and finally, for bad nesting, to the random antiferromagnetic state (RAF). Both SDW and dSC phases are affected by disorder. The pair breaking depends on the imperfect nesting and is the most efficient when the critical temperature for superconductivity is maximal.PACS numbers: 73.20.Fz Interesting and new physics appears when density wave (DW) and superconducting (SC) correlations interfere with each other and with the disorder. One finds realizations of such interferences in correlated electronic systems whose Fermi surface (FS) has at least imperfect nesting properties. The Bechgaard salts (TMTSF) 2 X and the Fabre salts (TMTTF) 2 X have two open quasi-onedimensional Fermi sheets responsible for DW correlations and, very probably, for superconductivity.[1] In these compounds the disorder strength can be tuned by the cooling speed or by x-ray irradiation, while the imperfect nesting is controlled either by chemical structure or by pressure. Another example of correlated system with important disorder effects are the two-dimensional (2D) organic compounds from the BEDT-TTF (ET) family.[1, 2] All ETs have a metal-insulator and/or a DW transition in the phase diagram. They have two FSs with several more or less perfect inter-and intra-band nesting wave vectors. Their superconductivity is induced by the DW fluctuations. In the high-T c superconductors the pseudogap and the superconducting states are both related to the antiferromagnetic (commensurate SDW) insulating phase. The effects of disorder on the high-T c superconductivity has been widely studied experimentally and theoretically. [6,7] It has been shown by a number of methods, and in particular by the angle resolved renormalization group (RG) that this interplay between the DW, the pseudogap and the SC exists in models with at least flat segments of the FS or with nested van Hove singularities. [3,4,5] However, no attempt has been made to implement both disorder and correlations in the Npatch RG, which would provide a perturbative, but nonbiased and controlled way for constructing the phase diagram.In this letter we report a perturbative angle-resolved (N-patch) RG theory for the model consisting of two flat FS segments in regard. The imperfect nesting parameter is treated approximately, by introducing a cut-off ǫ in the Peierls channel. For the pure case this problem was solved in the Parquet formulation by Zheleznyak et al [3] and later closely reexamined in the field-theoretical RG language.[8] While previous theories in more than...

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Impurity effects ind-wave superconductors

Cited by 216 publications

References 22 publications

Impurity scattering in f-wave superconductor UPt3

Impurity scattering in f-wave superconductor UPt3

Depression of Quasiparticle Density of States at Zero Energy inLa1.9Sr0.1Cu1−
Chang
¹
,
Lin
²
,
Yang
³

2000
Phys. Rev. Lett.

Effects of Nonmagnetic Impurities on Spin-Fluctuation Induced Superconductivity

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Impurity effects ind-wave superconductors

Cited by 216 publications

References 22 publications

Impurity scattering in f-wave superconductor UPt3

Impurity scattering in f-wave superconductor UPt3

Depression of Quasiparticle Density of States at Zero Energy inLa1.9Sr0.1Cu1−Chang1, Lin2, Yang3 2000Phys. Rev. Lett.

Effects of Nonmagnetic Impurities on Spin-Fluctuation Induced Superconductivity

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Depression of Quasiparticle Density of States at Zero Energy inLa1.9Sr0.1Cu1−
Chang
¹
,
Lin
²
,
Yang
³

2000
Phys. Rev. Lett.