Horizontal line nodes in superconducting Sr<sub>2</sub>RuO<sub>4</sub>

Litak, Grzegorz; Annett, James F.; Győrffy, Balázs; Wysokiński, Karol I.

doi:10.1002/pssb.200301978

Cited by 12 publications

(16 citation statements)

References 24 publications

(43 reference statements)

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“…Also, two-component odd-frequency gap functions can lead to observed Kerr rotation in SRO 44 . Also, our observation of nodal gap instabilities is consistent with nodal gap structures reported from several measurements and previous theoretical studies based on model Hamiltonians and first principles [45][46][47][48][49][50][51][52] . Table 1 shows how different gap structures transform under spin exchangeŜ, orbital exchangeÔ, time exchangeT, and paritŷ P operators.…”

Section: Discussionsupporting

confidence: 92%

Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$

et al. 2019

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Unconventional superconductivity in Sr 2 RuO 4 has been intensively studied for decades. However, the nature of pairing continues to be widely debated. Here we develop a detailed ab initio theory, coupling quasiparticle self-consistent GW approximation with dynamical mean field theory (DMFT), including both local and non-local correlations to address the subtle interplay among spin, charge and orbital degrees of freedom. We report that the superconducting instability has multiple triplet and singlet components. In the unstrained case the triplet eigenvalues are larger than the singlets. Under uniaxial strain, the triplet eigenvalues drop and the singlet components increase. This is concomitant with our observation of spin and charge fluctuations shifting closer to wave-vectors favoring singlet pairing. We identify a complex mechanism where charge fluctuations and spin fluctuations cooperate in the evenparity channel under strain leading to increment in critical temperature (Tc), thus proposing a novel mechanism for pushing the frontier of critical temperature (Tc) in unconventional 'triplet' superconductors.

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Section: Discussionsupporting

confidence: 92%

Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$

et al. 2019

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“…[7][8][9][10][11] Others insist that the assumption of horizontal nodes is more correct and promising. 1, [12][13][14][15][16][17][18][19] There have also been suggestions of point nodes. 20 Observation of a second superconducting phase 21 makes this problem even more complicated.…”

mentioning

confidence: 99%

Influence of hydrostatic pressure on the magnetic phase diagram of superconductingSr2RuO4by ultrasonic attenuation

et al. 2008

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The effect of high hydrostatic pressure on the magnetic field and temperature dependence of the attenuation of a longitudinal ultrasonic wave propagated along the ͗100͘ direction in superconducting Sr 2 RuO 4 has been investigated. The magnetic field dependence of the attenuation suggests the vertical character of the nodes in the superconducting gap. Application of pressure causes a decrease of the critical temperature T c and critical magnetic field H c2 ; the width of the transition under pressure increases. The dependence of H c2ʈab on T c was found to be linear, in contrast to the quadratic one for H c2ʈc . The slope dH c2ʈab / dT c has a universal character; its value does not depend on the physical factor causing reduction of T c , regardless if it is pressure or impurities. The observed effects demonstrate that the pressure application induces an increase in the electronelectron interaction. We show that this increase can be described in terms of a changing electron relaxation time, as in the case of impurities.The persistent interest in layered Sr 2 RuO 4 over the past dozen of years ͑for review see Refs. 1-3͒ is fueled by the unconventional spin-triplet superconductivity 4 and the rich variety of phenomena, related to this property. Some characteristics of this material, for example, two dimensionality of the electron liquid 5 and the Fermi surface topology, 6 have already been understood. At the same time, there is still no self-consistent superconductivity model for this material. In particular, the question of the gap structure is especially contradictory. Some authors believed that the best explanation of experimental results can be achieved with the assumption of vertical nodes. 7-11 Others insist that the assumption of horizontal nodes is more correct and promising. 1,12-19 There have also been suggestions of point nodes. 20 Observation of a second superconducting phase 21 makes this problem even more complicated. The lack of relevant experimental data, in particular, magnetoacoustic and high pressure, was discussed, for example, in Refs. 1, 22, and 23. Consequently, there is a clear motivation to perform more work on Sr 2 RuO 4 , diversifying the experimental techniques and conditions in an effort to obtain deeper insight into the nature of its superconductivity. We believe that our research is an important step in clarifying the gap node character. Among the other revealed phenomena, the linear dependence of the upper critical magnetic field, H c2ʈab , on T c is the most interesting one, especially that it is contrasting with the known 24 quadratic dependence for H c2ʈc .The Sr 2 RuO 4 single crystal was grown by the floating zone technique 25 in oxygen-reduced atmosphere at the rate of 30 mm/ h. The as-grown crystal was about 30 mm in length and 4 mm in diameter. Upon 100 h of annealing at 1000°C in O 2 atmosphere, the crystal was oriented and cut perpendicular to the ͗100͘ direction. The superconducting transition occurred at a temperature of T c = 1.2 K, which indicates the good quality of th...

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“…The Cooper pairs in Sr 2 RuO 4 are believed to be odd parity spin triplets (Litak et al, 2004), and the compound is said to exhibit time reversal symmetry breaking (Luke et al, 1998). It was pointed out that the only other spin triplet superconductors found in metals are the heavy Fermion compound UPt 3 , and the Bechgaard salt organic conductors (TMTSF) 2 X with the structure sketched in Fig.…”

Section: G Sr 2 Ruo 4 Compound (T Phase)mentioning

confidence: 99%

Cuprate high-Tc superconductors

et al. 2014

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Horizontal line nodes in superconducting Sr₂RuO₄

Cited by 12 publications

References 24 publications

Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$

Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$

Influence of hydrostatic pressure on the magnetic phase diagram of superconductingSr2RuO4by ultrasonic attenuation

Cuprate high-Tc superconductors

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Horizontal line nodes in superconducting Sr2RuO4

Cited by 12 publications

References 24 publications

Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$

Evening out the spin and charge parity to increase $${T}_{c}$$ in $${{\rm{Sr}}}_{2}{{\rm{RuO}}}_{4}$$

Influence of hydrostatic pressure on the magnetic phase diagram of superconductingSr2RuO4by ultrasonic attenuation

Cuprate high-Tc superconductors

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Horizontal line nodes in superconducting Sr₂RuO₄