Josephson coupling of YBa2Cu3O7−<i>x</i> through a ferromagnetic barrier SrRuO3

Antognazza, L.; Char, K.; Geballe, T. H.; King, L. L. H.; Sleight, A.W.

doi:10.1063/1.109878

Cited by 105 publications

(73 citation statements)

References 9 publications

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Section: 5mentioning

confidence: 99%

“…Interestingly, the supercurrent in the YBCO/SRO113/YBCO junction abruptly disappears when the thickness of the SRO113 layer exceeds 25 nm. 21,22 In another report, superconducting gap in a YBCO/SRO113(18-nm) bilayer persists only at the ferromagnetic domain-wall regions.23 Our findings of highly conducting interface between SRO113 and SRO214 open up a possibility to develop high-quality FM/TSC junctions to explore the unconventional proximity effects.The a-axis mismatch at 300 K between the bulk SRO113 (a 113 = 3.93Å in the pseudo-cubic notation) 24 and the bulk SRO214 (a 214 = 3.871Å) 14 is (a 113 − a 214 )/a 214 = 1.5%. This raises a possibility that a SRO113 (001) thin film can be grown on the absurface of SRO214 under compressive strain.…”

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confidence: 99%

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Ferromagnetic SrRuO₃ thin-film deposition on a spin-triplet superconductor Sr₂RuO₄ with a highly conducting interface

Anwar

Lee

Kang

et al. 2014

Appl. Phys. Express

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Ferromagnetic SrRuO3 thin films are deposited on the ab-surface of single crystals of the spin-triplet superconductor Sr2RuO4 as substrates using pulsed laser deposition. The films are under a severe in-plane compressive strain. Nevertheless, the films exhibit ferromagnetic order with the easy axis along the c-direction below the Curie temperature of 158 K. The electrical transport reveals that the SrRuO3/Sr2RuO4 interface is highly conducting, in contrast with the interface between other normal-metals and the ab-surface of Sr2RuO4. Our results will stimulate the investigations on proximity effects between a ferromagnet and a spin-triplet superconductor.Hybrid structures with ferromagnetic metals (FMs) and superconductors are fascinating systems exhibiting unconventional phenomena originating from competition and cooperation between the ferromagnetic order and superconductivity. In the past, two aspects of exotic behavior of the proximity effect between a FM and a spinsinglet superconductor (SSC) have been revealed. Firstly, the amplitude and phase of the spin-singlet order parameter spatially oscillates in the FM due to exchange interaction and even leads to a π-junction.1 The penetration length of this effect is intrinsically limited to the order of a few nanometers. Secondly, a spin-triplet pair amplitude emerges over a length of the order of a micrometer into the FM if suitable magnetic inhomogeneity is present at the FM/SSC interface.2-7 The resulting superconducting symmetry in the FM is spin-triplet s-wave and thus classified as odd-frequency pairing.8 To induce such a superconductivity into a ferromagnet, half metallic FM CrO 2 with multi-fold magnetic anisotropy, 3,6 or alternatively ferromagnetic multilayer X/Co/X, where X can be PdNi, CuNi, Ni, or Ho, with non-collinear magnetization, is used in the SSC/FM/SSC Josephson junctions. 4, 5, 7Another approach to realize novel superconducting junctions with FM is to use a spin-triplet superconductor (TSC) with multiple degrees of freedom of the order parameter.10-12 Indeed, it has been theoretically predicted that not only charge supercurrent but also spin supercurrent emerges at FM/TSC interface and both can be controlled by the magnetization direction in the FM relative to the direction of the spins of the spin triplet Cooper pairs.11 Thus, FM/TSC junctions, with both controllable charge and spin supercurrents, would initiate a new research area that can be termed as "Superspintronics".Most likely, Sr 2 RuO 4 (SRO214) exhibits the chiral pwave spin-triplet superconducting order parameter analogous to the superfluid 3 He-A phase. 13, 14 SRO214 has also been attracting much attention as one of the leading candidates for the topological superconductor. Recently, its topological nature has been investigated with superconducting junctions.15-17 The main challenge in realizing a FM/TSC junction is the availability of thin films of spin triplet superconductors. By overcoming the difficulty in growing high quality SRO214 films, superconductivity has finally been ...

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Section: 5mentioning

confidence: 99%

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confidence: 99%

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Ferromagnetic SrRuO₃ thin-film deposition on a spin-triplet superconductor Sr₂RuO₄ with a highly conducting interface

Anwar

Lee

Kang

et al. 2014

Appl. Phys. Express

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“…The combination of good chemical stability, good metallic conductivity [3], and easy epitaxial growth on various perovskite substrates [4][5][6] makes it attractive for possible multilayer device applications [7]. There is some evidence [8] that above ≈800K the structure reverts to cubic.…”

Section: Introductionmentioning

confidence: 99%

Transport properties, thermodynamic properties, and electronic structure ofSrRuO3

et al. 1996

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(today) SrRuO3 is a metallic ferromagnet. Its electrical resistivity is reported for temperatures up to 1000K; its Hall coefficient for temperatures up to 300K; its specific heat for temperatures up to 230K. The energy bands have been calculated by self-consistent spin-density functional theory, which finds a ferromagnetic ordered moment of 1.45µB per Ru atom. The measured linear specific heat coefficient γ is 30mJ/mole, which exceeds the theoretical value by a factor of 3.7. A transport mean free path at room temperature of ≈ 10Å is found. The resistivity increases nearly linearly with temperature to 1000K in spite of such a short mean free path that resistivity saturation would be expected. The Hall coefficient is small and positive above the Curie temperature, and exhibits both a low-field and a high-field anomalous behavior below the Curie temperature.65.40. Em,75.40.Cx,71.25.Pi,72.15.Eb,72.15.Gd

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“…From the point of view of possible technological applications, both the crystallographic structure ͑pseudocubic perovskite͒ and lattice parameters of this material, close to those of ͑YBCO͒, make it a promising candidate for the fabrication of ͑SNS͒ Josephson junctions of high-T c superconducting oxides. 7 In addition, its conducting character makes it a suitable material for electrodes in other types of devices based on perovskite oxides, as epitaxial conducting oxide-ferroelectric or superconduction-ferroelectric heterostructures. 8 Structural distortions are known to play a central role in the magnetic properties of SrRuO 3 .…”

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Metal–insulator transition in SrRuO3 induced by ion irradiation

Sefrioui

Arias

Navacerrada

et al. 1998

Applied Physics Letters

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We have studied the effect of He ϩ irradiation on the electrical resistivity and Curie temperature of ferromagnetic SrRuO 3 thin films. An evolution from metallic to insulating behavior is observed when He ϩ ion fluence is increased, suggesting a metal-insulator transition. Damage by ion irradiation produces a strong decrease of the Curie temperature. On the other hand, no significant change in T c ͑ϳ160 K͒ takes place in fresh samples grown at different substrate temperatures. We discuss the possible correlation between structural changes induced by irradiation, which reflect in an increase of the pseudocubic lattice parameter, and the observed depression of T c . © 1998 American Institute of Physics. ͓S0003-6951͑98͒03349-X͔ SrRuO 3 is an orthorhombically distorted perovskite ͑space group Pbnm͒, and the only example of ferromagnetic ordering ͑with a Curie temperature T c , of 165 K͒ in conducting 4d transition-metal oxides. 1,2 This compound has a 4d 4 low spin configuration (Sϭ1) and is believed to have a narrow * band resulting from Ru t 2g and O 2 p orbitals, which governs magnetic ordering. 3,4 The actual nature of magnetism in this material, usually considered as an example of pure itinerant magnetism, 5 is not fully understood yet. This system can be included in the group of the so-called ''bad metals,'' 5,6 strongly correlated electron systems showing remarkable electrical and magnetic properties. A common feature of these materials is the high value of their roomtemperature electrical resistivities, close to the theoretical limit for the metallic state ͑Ioffe-Regel limit͒. From the point of view of possible technological applications, both the crystallographic structure ͑pseudocubic perovskite͒ and lattice parameters of this material, close to those of ͑YBCO͒, make it a promising candidate for the fabrication of ͑SNS͒ Josephson junctions of high-T c superconducting oxides. 7 In addition, its conducting character makes it a suitable material for electrodes in other types of devices based on perovskite oxides, as epitaxial conducting oxide-ferroelectric or superconduction-ferroelectric heterostructures. 8 Structural distortions are known to play a central role in the magnetic properties of SrRuO 3 . The absence of ferromagnetic ordering in the isostructural CaRuO 3 has been explained in terms of a stronger orthorhombical distortion in this compound which changes the sign of the magnetic interaction. 9 Both hydrostatic and chemical pressure resulting from the partial substitution of Sr 2ϩ ͑0.62 A͒ by the bigger Ca 2ϩ ͑1.06 A͒ give rise to a decrease of the Curie temperature, but the system remains metallic. This has been explained in terms of the magnetism of this compound being very sensitive to the Ru-Ru distance. 10 On the other hand, substitution of Ru by Ti up to 20% rapidly reduces the critical temperature and causes an increase of the resistivity which undergoes a crossover from metallic to semiconducting behavior at low temperatures. Once again, this has been proposed to occur as a result of local ...

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Josephson coupling of YBa2Cu3O7−x through a ferromagnetic barrier SrRuO3

Cited by 105 publications

References 9 publications

Ferromagnetic SrRuO₃ thin-film deposition on a spin-triplet superconductor Sr₂RuO₄ with a highly conducting interface

Ferromagnetic SrRuO₃ thin-film deposition on a spin-triplet superconductor Sr₂RuO₄ with a highly conducting interface

Transport properties, thermodynamic properties, and electronic structure ofSrRuO3

Metal–insulator transition in SrRuO3 induced by ion irradiation

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Josephson coupling of YBa2Cu3O7−x through a ferromagnetic barrier SrRuO3

Cited by 105 publications

References 9 publications

Ferromagnetic SrRuO3 thin-film deposition on a spin-triplet superconductor Sr2RuO4 with a highly conducting interface

Ferromagnetic SrRuO3 thin-film deposition on a spin-triplet superconductor Sr2RuO4 with a highly conducting interface

Transport properties, thermodynamic properties, and electronic structure ofSrRuO3

Metal–insulator transition in SrRuO3 induced by ion irradiation

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Product

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Ferromagnetic SrRuO₃ thin-film deposition on a spin-triplet superconductor Sr₂RuO₄ with a highly conducting interface

Ferromagnetic SrRuO₃ thin-film deposition on a spin-triplet superconductor Sr₂RuO₄ with a highly conducting interface