Effects of deep superconducting gap minima and disorder on residual thermal transport in 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>Sr</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>RuO</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:math>

Dodaro, John F.; Wang, Zhiqiang; Kallin, Catherine

doi:10.1103/physrevb.98.214520

Cited by 11 publications

(12 citation statements)

References 69 publications

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“…Deep vertical minima, as first predicted in two dimensions 46,52 , are present on all three bands. Notably, the gap on the β band has min θ |∆ β (θ, k z ≈ π)| 0.02∆ 0 , where θ is the in-plane azimuthal angle and ∆ 0 the maximal gap, at locations in agreement with previous predictions 16,46,53 . The minima are deep enough to practically behave as accidental vertical nodes, and to provide a decent agreement with specific heat data, see Fig.…”

supporting

confidence: 89%

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Superconducting order of Sr2RuO4 from a three-dimensional microscopic model

Røising¹,

Scaffidi

Flicker³

et al. 2019

Phys. Rev. Research

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We compute and compare even-and odd-parity superconducting order parameters of strontium ruthenate (Sr2RuO4) in the limit of weak interactions, resulting from a fully microscopic threedimensional model including spin-orbit coupling. We find that odd-parity helical and even-parity dwave order are favored for smaller and larger values of the Hund's coupling parameter J, respectively. Both orders are found compatible with specific heat data and the recently-reported nuclear magnetic resonance (NMR) Knight shift drop [A. Pustogow et al. arXiv:1904.00047 (2019]. The chiral p-wave order, numerically very competitive with helical order, sharply conflicts with the NMR experiment.

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supporting

confidence: 89%

“…4 (a). The character of the minima also appear likely to agree with thermal Hall measurements 15,16 .…”

supporting

confidence: 68%

Superconducting order of Sr2RuO4 from a three-dimensional microscopic model

Røising¹,

Scaffidi

Flicker³

et al. 2019

Phys. Rev. Research

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“…1500 ppm, where the impurities act as strong scattering centers. As another characteristic of unconventional superconductivity, the quasiparticle density of states readily emerges within the superconducting gap even with a small amount of impurities and defects [11]; the resulting large residual density of states often makes the determination of the intrinsic gap anisotropy a challenging issue [12][13][14][15]. Furthermore, some unusual superconducting phenomena occur only in very high-purity crystals: the superconducting transition with a magnetic field applied parallel to the RuO 2 plane becomes first order at low temperatures [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Improved Single-Crystal Growth of Sr2RuO4

et al. 2019

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High-quality single crystals are essentially needed for the investigation of the novel bulk properties of unconventional superconductors. The availability of such crystals grown by the floating-zone method has helped to unveil the unconventional superconductivity of the layered perovskite Sr 2 RuO 4 , which is considered as a strong candidate of a topological spin-triplet superconductor. Yet, recent progress of investigations urges further efforts to obtain ultimately high-quality crystalline samples. In this paper, we focus on the method of preparation of feed rods for the floating-zone melting and report on the improvements of the crystal growth. We present details of the improved methods used to obtain crystals with superconducting transition temperatures T c that are consistently as high as 1.4 K, as well as the properties of these crystals.Despite the key experimental results supporting spin-triplet pairing [19][20][21][22][23], such a first-order transition is difficult to explain within the context of spin-triplet superconductivity. This first-order transition becomes second order when the T c is suppressed below 1.45 K, which corresponds to an impurity level of~50 ppm [10]. Thus, pristine samples with impurity levels less than 10 ppm are required in order to deepen our knowledge of the superconducting state of Sr 2 RuO 4 .Recent innovations in the design of uniaxial-stress cells enables the T c of Sr 2 RuO 4 to be enhanced up to 3.5 K when the stress is along the crystalline [100] direction [24][25][26][27]. The origin of this enhancement of T c is attributed to the Fermi-level crossing of the van-Hove singularity in one of the three quasi-two-dimensional Fermi surfaces. It is hoped that detailed investigations of this phenomenon will lead to the clarification of the superconducting symmetry and mechanism in Sr 2 RuO 4 . The T c enhancement has actually been known for many years in the eutectic crystals of Sr 2 RuO 4 with micron-size metallic Ru platelets, which introduce strong strains in Sr 2 RuO 4 near the interfaces [28][29][30]. In order to investigate the strain-induced superconducting phase, high-quality Ru-inclusion free single crystals of Sr 2 RuO 4 with a specific in-plane crystalline direction are in demand.In this study, we examine how we can further improve the quality of crystals of Sr 2 RuO 4 grown by the floating-zone method with an infrared image furnace. The floating-zone technique has been used to produce high-quality crystals of relatively large size useful for most experimental purposes including inelastic neutron scattering. Because the technique is essentially crucible-free, it can be used to achieve the minimum possible impurity levels. The floating-zone technique has been used for the successful crystal growth of Sr 2 RuO 4 [31], as well as other ruthenates [32][33][34][35][36][37]. Previous reports mainly describe optimization of the atomic compositions of the feed rod and various parameters of the final growth process. On the other hand, there are a number of processes (from pow...

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“…Although the d + ig candidate may reconcile a number of experiments, a robust justification for a near degeneracy of d and g-wave order parameters is yet to be found. This outstanding issue is even more apparent when bearing in mind that numerous calculations based on realistic band structures have yet to find a competitive g-wave order parameter [13,[22][23][24]26,27,30,[57][58][59][60].…”

Section: Discussionmentioning

confidence: 99%

“…In addition to Ref. [24], several other RG calculations have been performed [23,26,[57][58][59][60][61], finding slightly different competing order parameters. However, one should not expect the shape of aμ (p) for a given a and μ to be vastly different in the multiple different approaches.…”

Section: A the Relative Order Parameter Weightmentioning

confidence: 99%

Microscopic Ginzburg-Landau theory and singlet ordering inSr2RuO4

et al. 2021

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The long-standing quest to determine the superconducting order of Sr 2 RuO 4 (SRO) has received renewed attention after recent nuclear magnetic resonance (NMR) Knight shift experiments have cast doubt on the possibility of spin-triplet pairing in the superconducting state. As a putative solution, encompassing a body of experiments conducted over the years, a (d + ig)-wave order parameter caused by an accidental near degeneracy has been suggested [S. A. Kivelson et al., npj Quantum Mater. 5, 43 (2020)]. Here we develop a general Ginzburg-Landau theory for multiband superconductors. We apply the theory to SRO and predict the relative size of the order parameter components. The heat capacity jump expected at the onset of the second-order parameter component is found to be above the current threshold deduced by the experimental absence of a second jump. Our results tightly restrict theories of d + ig order, and other candidates caused by a near degeneracy, in SRO. We discuss possible solutions to the problem.

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Effects of deep superconducting gap minima and disorder on residual thermal transport in Sr2RuO4

Cited by 11 publications

References 69 publications

Superconducting order of Sr2RuO4 from a three-dimensional microscopic model

Superconducting order of Sr2RuO4 from a three-dimensional microscopic model

Improved Single-Crystal Growth of Sr2RuO4

Microscopic Ginzburg-Landau theory and singlet ordering inSr2RuO4

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