<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mmultiscripts><mml:mrow><mml:mi>O</mml:mi></mml:mrow><mml:mprescripts /><mml:mrow /><mml:mrow><mml:mn>17</mml:mn></mml:mrow><mml:mrow /><mml:mrow /></mml:mmultiscripts></mml:mrow></mml:math>NMR Evidence for Orbital Dependent Ferromagnetic Correlations in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>Sr</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:

Imai, Takashi; Hunt, A. W.; Thurber, Kent R.; Chou, F. C.

doi:10.1103/physrevlett.81.3006

Cited by 134 publications

(169 citation statements)

References 19 publications

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“…The dynamic susceptibility at moderate ener-gies is indeed dominated by the incommensurate fluctuations occurring very close to the calculated position at q i = (0.30, 0.30, 0). Furthermore, we found a pronounced temperature dependence which can explain the temperature dependence of both Ru-and O-1 T1T -NMR [10]. In the meanwhile, several groups have worked on theories where superconductivity is related to the incommensurate fluctuations [21,22,23].…”

Section: Introductionmentioning

confidence: 79%

“…Rice and Sigrist stressed the comparison with the perovskites SrRuO 3 and CaRuO 3 which order ferromagnetically or are nearly ferromagnetic respectively [9]. Evidence for ferromagnetic fluctuations in Sr 2 RuO 4 was inferred from NMR-experiments : Imai et al found that 1 T1T of the Oand of the Ru-NMR exhibit a similar temperature dependence and interpreted that this could be only due to ferromagnetic fluctuations [10].…”

Section: Introductionmentioning

confidence: 99%

“…Due to the agreement between the INS results and the RPA calculations, we suggest to interpret the additional broad scattering as being magnetic in origin; however, a polarized neutron study would be highly desirable. This scattering further might be relevant for a quantitative explanation of the NMR-data [10,20], in particular its temperature independent part. Sr 2 RuO 4 is not close to ferromagnetic order but substitution of Sr through Ca yields such order for the concentration Ca 1.5 Sr 0.5 RuO 4 [15].…”

Section: Possible Additional Magnetic Excitationsmentioning

confidence: 99%

“…In reference [20] we have compared the temperature dependence of the incommensurate signal with that of the spin-lattice relaxation rate T 1 measured by both 17 O and 101 Ru NMR experiments [10]. These NMR-techniques probe the low energy spin fluctuations (ω → 0 with respect to INS measurements); furthermore, they integrate the fluctuations in q-space.…”

Section: Combined Temperature and Energy Dependence Of The Incommementioning

confidence: 99%

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Inelastic neutron scattering study of magnetic excitations inSr2RuO4

et al. 2002

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Magnetic excitations in Sr2RuO4 have been studied by inelastic neutron scattering. The magnetic fluctuations are dominated by incommensurate peaks related to the Fermi surface nesting of the quasi-one-dimensional dxz-and dyz-bands. The shape of the incommensurate signal agrees well with RPA calculations. At the incommensurate Q-positions the energy spectrum considerably softens upon cooling pointing to a close magnetic instability : Sr2RuO4 does not exhibit quantum criticality but is very close to it. ω/T -scaling may be fitted to the data for temperatures above 30 K. Below the superconducting transition, the magnetic response at the nesting signal is not found to change in the energy range down to 0.4meV.

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Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Possible Additional Magnetic Excitationsmentioning

confidence: 99%

Section: Combined Temperature and Energy Dependence Of The Incommementioning

confidence: 99%

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Inelastic neutron scattering study of magnetic excitations inSr2RuO4

et al. 2002

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“…Although it is now widely believed that the unconventional nature of SC in this compound is mediated by spin fluctuations, the exact nature of this interaction is still unresolved. Originally, it was suggested that ferromagnetic (FM) spin fluctuations were responsible for mediating the SC as inferred from theoretical calculations, 4 NMR measurements, 5 and ferromagnetism in closely related SrRuO 3 . However, more recent evidence has suggested that this simple picture may be incomplete.…”

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confidence: 99%

Surface electronic structure ofSr2RuO4

Shen

Damascelli

et al. 2001

Phys. Rev. B

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We have addressed the possibility of surface ferromagnetism in Sr2RuO4 by investigating its surface electronic states by angle-resolved photoemission spectroscopy (ARPES). By cleaving samples under different conditions and using various photon energies, we have isolated the surface from the bulk states. A comparison with band structure calculations indicates that the ARPES data are most readily explained by a nonmagnetic √ 2 × √ 2 surface reconstruction.Following the discovery of superconductivity (SC) at 1 K in the layered perovskite Sr 2 RuO 4 , 1 the exact nature of its SC pairing mechanism has attracted a great deal of interest. While it shares the same structure as the archetypal cuprate parent compound La 2 CuO 4 , RuO 2 planes replace the CuO 2 planes thus resulting in an anisotropic Fermi liquid 2 instead of a strongly correlated charge transfer insulator. Furthermore, there is evidence that Sr 2 RuO 4 exhibits spin-triplet pairing with a p-wave order parameter, 3 as opposed to the spin-singlet, d-wave symmetry found in the cuprates. Although it is now widely believed that the unconventional nature of SC in this compound is mediated by spin fluctuations, the exact nature of this interaction is still unresolved. Originally, it was suggested that ferromagnetic (FM) spin fluctuations were responsible for mediating the SC as inferred from theoretical calculations, 4 NMR measurements, 5 and ferromagnetism in closely related SrRuO 3 . However, more recent evidence has suggested that this simple picture may be incomplete. Antiferromagnetism (AFM) in Ca 2 RuO 4 , the observation of incommensurate peaks at Q = (0.6π, 0.6π, 0) by neutron scattering, 6 and calculations which show strong nesting at Q = (2π/3, 2π/3, 0) 7 all seem to imply AFM correlations should not be neglected, leaving the nature of SC open to speculation.Recently, an analysis of low-energy electron diffraction data from Sr 2 RuO 4 indicated that a √ 2 × √ 2 reconstruction was induced by the freezing of a soft zone boundary phonon into a static lattice distortion at the surface, and comparisons with band structure calculations predicted that the resulting surface was FM. 8 This conjecture also appears conceivable in light of speculation based on recent ARPES results 9 as well as earlier theoretical calculations. 10 If FM does exist on the surface of Sr 2 RuO 4 , such a result should be indicative of strong ferromagnetic tendencies in the bulk and thus possibly relevant to microscopic theories which describe the mechanism of SC. This speculation becomes even more intriguing in light of recent STM measurements 11 which suggest the opening of a superconducting gap with T c = 1.4 K, perhaps hinting that the surface layer may be superconducting, and raises the possibility that the surface of Sr 2 RuO 4 may exhibit the rare coexistence of SC and FM. However, as this proposed surface FM has never been confirmed, it becomes imperative to reinvestigate the surface electronic structure to definitively verify or exclude surface FM.In this paper, we present a ...

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Unconventional superconductivity and magnetism in Sr2RuO4 and related materials

et al. 2004

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Key words unconventional triplet superconductivity, spin fluctuations, strong electronic correlations PACS 74.20.Mn, 74.70.Pq We review the normal and superconducting state properties of the unconventional triplet superconductor Sr2RuO4 with an emphasis on the analysis of the magnetic susceptibility and the role played by strong electronic correlations. In particular, we show that the magnetic activity arises from the itinerant electrons in the Ru d-orbitals and a strong magnetic anisotropy occurs (χ +− < χ zz ) due to spin-orbit coupling. The latter results mainly from different values of the g-factor for the transverse and longitudinal components of the spin susceptibility (i.e. the matrix elements differ). Most importantly, this anisotropy and the presence of incommensurate antiferromagnetic and ferromagnetic fluctuations have strong consequences for the symmetry of the superconducting order parameter. In particular, reviewing spin fluctuation-induced Cooper-pairing scenario in application to Sr2RuO4 we show how p-wave Cooper-pairing with line nodes between neighboring RuO2-planes may occur.We also discuss the open issues in Sr2RuO4 like the influence of magnetic and non-magnetic impurities on the superconducting and normal state of Sr2RuO4. It is clear that the physics of triplet superconductivity in Sr2RuO4 is still far from being understood completely and remains to be analyzed more in more detail. It is of interest to apply the theory also to superconductivity in heavy-fermion systems exhibiting spin fluctuations.

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O17NMR Evidence for Orbital Dependent Ferromagnetic Correlations inSr2

Cited by 134 publications

References 19 publications

Inelastic neutron scattering study of magnetic excitations inSr2RuO4

Inelastic neutron scattering study of magnetic excitations inSr2RuO4

Surface electronic structure ofSr2RuO4

Unconventional superconductivity and magnetism in Sr2RuO4 and related materials

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