Suppression of superconductivity in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">RuO</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>caused by defects

Mao, Z. Q.; Mori, Y.; Maeno, Y.

doi:10.1103/physrevb.60.610

Cited by 91 publications

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“…While the slight deviation of the scattering phase shift from π/2 might be able to explain it [6], the calculated steep increase of κ 00 /T [3] is inappropriate for the description of Sr 2 RuO 4 . The critical resistivity, above which T c disappears, is about 1 µΩcm [18,19] and the corresponding critical κ/T is obtained by the Wiedemann-Franz law as 2.4 W/K 2 m, which is almost equal to our largest κ 00 /T . Since there is no clear reason for κ/T at T =0 K to become higher in the SC state than in the normal state, the increase of κ 00 /T with Γ expected in Ref.…”

Section: ∂∆(φ)mentioning

confidence: 80%

“…The T c and the transition width δT c were defined at the peak temperature and the full width at half maximum of the imaginary part of the AC susceptibility, respectively (Table I). The difference in T c comes from the variation of the density of non-magnetic impurities, such as Al or Si [18], and/or crystalline defects [19]. The sys-tematic studies on the electrical resistivity ρ and resistive T c revealed that the suppression of T c is well described by the Abrikosov-Gorkov type equation [34],…”

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confidence: 99%

“…This material has a layered perovskite structure [15] and its electronic state is well described in the Landau-Fermi liquid model [16]. The SC state of Sr 2 RuO 4 (T c = 1.5 K) is chiral with a broken time reversal symmetry [17] and its T c is rapidly suppressed by non-magnetic impurities [18,19]. Views on the SC gap symmetry of Sr 2 RuO 4 changed in time.…”

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Universal Heat Transport inSr2RuO4

et al. 2002

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We present the temperature dependence of the thermal conductivity κ(T ) of the unconventional superconductor Sr2RuO4 down to low temperatures (∼100 mK). In T → 0 K limit we found a finite residual term in κ/T , providing clear evidence for the superconducting state with an unconventional pairing. The residual term remains unchanged for samples with different Tc, demonstrating the universal character of heat transport in this spin-triplet superconductor. The low-temperature behavior of κ suggests the strong impurity scattering with a phase shift close to π/2. A criterion for the observation of universality is experimentally deduced.PACS numbers: 74.20. Rp, 74.25.Fy, 74.70.Pq Through the study of the cuprate superconductor in the last decade, a notable progress has been made in an understanding of the thermodynamic and transport properties of quasi-particles (QP) in unconventional superconductors. One of the important findings is the novel phenomenon called the universal transport, pointed out first by Lee [1]. In an unconventional superconductor with nodes in the superconducting (SC) gap, nonmagnetic impurities suppress the transition temperature (T c ) and induce the finite density of QP states at the Fermi level with the energy width γ imp [2]. The presence of impurities increases both the QP density and the impurity scattering rate, which completely cancel each other [3,4]. In this case the QP transport, such as thermal conductivity (κ), restores the temperature (T ) dependence typical for the normal state (e.g. κ ∝ T ) [5] and becomes independent of impurity concentration. The magnitude of the residual term in κ/T depends only on the QP spectrum near the gap nodes, providing a useful tool for studying the SC order parameter [4].Experimentally, the universal residual term in κ/T at T → 0 K has been reported in optimally-doped high-T c cuprates YBa 2 Cu 3 O 6.9 [6] and Bi 2 Sr 2 CaCu 2 O 8 [7,8].Their residual values are consistent with the d-wave SC gap structure [9]. For non-d-wave gap symmetries, the universal conductivity has never been observed. In contrast, the extrapolated κ/T at T → 0 K of the spin-triplet superconductor UPt 3 [10,11] rapidly increases with the density of defects, showing no universal behavior, and the residual term seems to vanish in zero-disorder limit [11]. The origin of the lack of universality is still unclear, similar to the case of under-doped cuprates [12], and it is strongly desirable to extend studies to other unconventional superconductors.In this respect, of special interest is the study of Sr 2 RuO 4 , a unique quasi-two-dimensional (Q2D) spin triplet superconductor [13,14]. This material has a layered perovskite structure [15] and its electronic state is well described in the Landau-Fermi liquid model [16]. The SC state of Sr 2 RuO 4 (T c = 1.5 K) is chiral with a broken time reversal symmetry [17] and its T c is rapidly suppressed by non-magnetic impurities [18,19]. Views on the SC gap symmetry of Sr 2 RuO 4 changed in time. Early theoretical prediction of the fully ga...

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Section: ∂∆(φ)mentioning

confidence: 80%

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Universal Heat Transport inSr2RuO4

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“…Using known material parameters [4], and scattering time τ ∼ 10 −11 sec (mean free path ∼ 1 µm), extracted from the residual resistivity of similar samples [4,25], we obtain θ K ∼ 100 nanorad. This estimate is very close to the observed saturation signal of ∼ 65 nanorad.…”

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High Resolution Polar Kerr Effect Measurements ofSr2RuO4: Evidence for Broken Time-Reversal Symmetry in the Superconducting State

et al. 2006

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Polar Kerr effect in the spin-triplet superconductor Sr2RuO4 was measured with high precision using a Sagnac interferometer with a zero-area Sagnac loop. We observed non-zero Kerr rotations as big as 65 nanorad appearing below Tc in large domains. Our results imply a broken time reversal symmetry state in the superconducting state of Sr2RuO4, similar to 3 He-A.PACS numbers: 74.25. Gz,74.70.Pq,74.25.Ha,78.20.Ls Soon after the discovery of the layered-perovskite superconductor Sr 2 RuO 4 [1], it was predicted to be an oddparity superconductor [2,3]. Subsequently, a large body of experimental results in support of odd-parity superconductivity has been obtained [4], with the most recent one being a phase-sensitive measurement [5]. The symmetry of the superconducting state is related simply to the relative orbital angular momentum of the electrons in each Cooper pair. Odd parity corresponds to odd orbital angular momentum and symmetric spin-triplet pairing. While a priori the angular momentum state can be p (i.e. L = 1), f ( i.e. L = 3), or even higher order [6,7], theoretical analyses of superconductivity in Sr 2 RuO 4 favor the p-wave order parameter symmetry [2,8]. There are many allowed p-wave states that satisfy the cylindrical Fermi surface for a tetragonal crystal which is the case of Sr 2 RuO 4 (see e.g. table IV in [4]). Some of these states break time-reversal symmetry (TRS), since the condensate has an overall magnetic moment because of either the spin or orbital (or both) parts of the pair wave function. While an ideal sample will not exhibit a net magnetic moment, surfaces and defects at which the Meissner screening of the TRS-breaking moment is not perfect can result in a small magnetic signal [7]. Indeed, muon spin relaxation (µSR) measurements on good quality single crystals of Sr 2 RuO 4 showed excess relaxation that spontaneously appear at the superconducting transition temperature. The exponential nature of the increased relaxation suggested that its source is a broad distribution of internal fields, of strength ∼ 0.5 Oe, from a dilute array of sources [9,10]. While TRS breaking is not the only explanation for the µSR observations, it was accepted as the most likely one [4]. However, since the existence of TRS breaking has considerable implications for understanding the superconductivity of Sr 2 RuO 4 , establishing the existence of this effect, and in particular in the bulk without relying on imperfections and defects is of utmost importance. The challenge is therefore to couple to the TRS-breaking part of the order parameter to demonstrate the effect unambiguously.In this paper we show results of polar Kerr effect (PKE) measurements on high quality single crystals of Sr 2 RuO 4 . In these measurements we are searching for an effect analogous to the magneto-optic Kerr effect (MOKE) which would cause a rotation of the direction of polarization of the reflected linearly polarized light normally incident to the superconducting planes. PKE is sensitive to TRS breaking since it measures the existenc...

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“…¿ÕÑÏÖ ÔÑÑÕÐÑÛÇÐËá ÖAEÑÄÎÇÕÄÑÓâáÕ ÍÂÍ AEÂÐÐÞÇ [51], ÕÂÍ Ë AEÂÐÐÞÇ ÒÓÇAEÞAEÖÜËØ ÓÂÃÑÕ [55,56]. ¥Îâ ÑÒÓÇAEÇÎÇÐËâ AEÎËÐÞ ÔÄÑÃÑAEÐÑÅÑ ÒÓÑÃÇÅÂ l ÐÂ ÑÔÐÑÄÇ ËÊÏÇÓÇÐËÌ ÑÔÕÂ-ÕÑÚÐÑÅÑ ÔÑÒÓÑÕËÄÎÇÐËâ r 0 ËÔÒÑÎßÊÑÄÂÎÂÔß ×ÑÓÏÖÎÂ [57].…”

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Exotic superconductivity and magnetism in ruthenates

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2003

Usp. Fiz. Nauk

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Suppression of superconductivity inSr2RuO4caused by defects

Cited by 91 publications

References 12 publications

Universal Heat Transport inSr2RuO4

Universal Heat Transport inSr2RuO4

High Resolution Polar Kerr Effect Measurements ofSr2RuO4: Evidence for Broken Time-Reversal Symmetry in the Superconducting State

Exotic superconductivity and magnetism in ruthenates

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