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Norman O. Birge - One of the best experts on this subject based on the ideXlab platform.
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spin triplet supercurrent in josephson junctions containing a synthetic antiferromagnet with perpendicular magnetic anisotropy
Physical Review B, 2017Co-Authors: Joseph A Glick, Reza Loloee, Norman O. Birge, W. P. Pratt, Samuel Edwards, Demet Korucu, Victor Aguilar, Bethany Niedzielski, Paul G KotulaAbstract:We present measurements of Josephson junctions containing three magnetic layers with noncolinear Magnetizations. The junctions are of the form $S/F^{\prime}/N/F/N/F^{\prime \prime}/S$, where $S$ is superconducting Nb, $F^\prime$ is either a thin Ni or Permalloy layer with in-plane Magnetization, $N$ is the normal metal Cu, $F$ is a synthetic antiferromagnet (SAF) with Magnetization perpendicular to the plane, composed of Pd/Co multilayers on either side of a thin Ru spacer, and $F^{\prime \prime}$ is a thin Ni layer with in-plane Magnetization. The supercurrent in these junctions decays more slowly as a function of the $F$-layer thickness than for similar spin-singlet junctions not containing the $F^\prime$ and $F^{\prime \prime}$ layers. The slower decay is the prime signature that the supercurrent in the central part of these junctions is carried by spin-triplet pairs. The junctions containing $F^{\prime}=$ Permalloy are suitable for future experiments where either the amplitude of the critical current or the ground-state phase difference across the junction is controlled by changing the relative orientations of the Magnetizations of the $F^{\prime}$ and $F^{\prime \prime}$ layers.
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amplitude control of the spin triplet supercurrent in s f s josephson junctions
Physical Review Letters, 2016Co-Authors: William Martinez, W. P. Pratt, Norman O. BirgeAbstract:Josephson junctions made with conventional s-wave superconductors and containing multiple layers of ferromagnetic materials can carry spin-triplet supercurrent in the presence of certain types of magnetic inhomogeneity. In junctions containing three ferromagnetic layers, the triplet supercurrent is predicted to be maximal when the Magnetizations of the adjacent layers are orthogonal, and zero when the Magnetizations of any two adjacent layers are parallel. Here we demonstrate on-off control of the spin-triplet supercurrent in such junctions, achieved by rotating the Magnetization direction of one of the three layers by 90°. We obtain “on-off” ratios of 5, 7, and 19 for the supercurrent in the three samples that have been studied so far. In conclusion, these observations directly confirm one of the most salient predictions of the theory, and they pave the way for applications of spin-triplet Josephson junctions in the nascent area of “superconducting spintronics”.
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spin triplet supercurrent in co ni multilayer josephson junctions with perpendicular anisotropy
Physical Review B, 2012Co-Authors: E C Gingrich, P Quarterman, Reza Loloee, W. P. Pratt, Yixing Wang, Norman O. BirgeAbstract:We have measured spin-triplet supercurrent in Josephson junctions of the form S/F'/F/F'/S, where S is superconducting Nb, F' is a thin Ni layer with in-plane Magnetization, and F is a Ni/[Co/Ni]n multilayer with out-of-plane Magnetization. The supercurrent in these junctions decays very slowly with F-layer thickness, and is much larger than in similar junctions not containing the two F' layers. Those two features are the characteristic signatures of spin-triplet supercurrent, which is maximized by the orthogonality of the Magnetizations in the F and F' layers. Magnetic measurements confirm the out-of-plane anisotropy of the Co/Ni multilayers. These samples have their critical current optimized in the as-prepared state, which will be useful for future applications.
W. P. Pratt - One of the best experts on this subject based on the ideXlab platform.
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spin triplet supercurrent in josephson junctions containing a synthetic antiferromagnet with perpendicular magnetic anisotropy
Physical Review B, 2017Co-Authors: Joseph A Glick, Reza Loloee, Norman O. Birge, W. P. Pratt, Samuel Edwards, Demet Korucu, Victor Aguilar, Bethany Niedzielski, Paul G KotulaAbstract:We present measurements of Josephson junctions containing three magnetic layers with noncolinear Magnetizations. The junctions are of the form $S/F^{\prime}/N/F/N/F^{\prime \prime}/S$, where $S$ is superconducting Nb, $F^\prime$ is either a thin Ni or Permalloy layer with in-plane Magnetization, $N$ is the normal metal Cu, $F$ is a synthetic antiferromagnet (SAF) with Magnetization perpendicular to the plane, composed of Pd/Co multilayers on either side of a thin Ru spacer, and $F^{\prime \prime}$ is a thin Ni layer with in-plane Magnetization. The supercurrent in these junctions decays more slowly as a function of the $F$-layer thickness than for similar spin-singlet junctions not containing the $F^\prime$ and $F^{\prime \prime}$ layers. The slower decay is the prime signature that the supercurrent in the central part of these junctions is carried by spin-triplet pairs. The junctions containing $F^{\prime}=$ Permalloy are suitable for future experiments where either the amplitude of the critical current or the ground-state phase difference across the junction is controlled by changing the relative orientations of the Magnetizations of the $F^{\prime}$ and $F^{\prime \prime}$ layers.
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amplitude control of the spin triplet supercurrent in s f s josephson junctions
Physical Review Letters, 2016Co-Authors: William Martinez, W. P. Pratt, Norman O. BirgeAbstract:Josephson junctions made with conventional s-wave superconductors and containing multiple layers of ferromagnetic materials can carry spin-triplet supercurrent in the presence of certain types of magnetic inhomogeneity. In junctions containing three ferromagnetic layers, the triplet supercurrent is predicted to be maximal when the Magnetizations of the adjacent layers are orthogonal, and zero when the Magnetizations of any two adjacent layers are parallel. Here we demonstrate on-off control of the spin-triplet supercurrent in such junctions, achieved by rotating the Magnetization direction of one of the three layers by 90°. We obtain “on-off” ratios of 5, 7, and 19 for the supercurrent in the three samples that have been studied so far. In conclusion, these observations directly confirm one of the most salient predictions of the theory, and they pave the way for applications of spin-triplet Josephson junctions in the nascent area of “superconducting spintronics”.
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spin triplet supercurrent in co ni multilayer josephson junctions with perpendicular anisotropy
Physical Review B, 2012Co-Authors: E C Gingrich, P Quarterman, Reza Loloee, W. P. Pratt, Yixing Wang, Norman O. BirgeAbstract:We have measured spin-triplet supercurrent in Josephson junctions of the form S/F'/F/F'/S, where S is superconducting Nb, F' is a thin Ni layer with in-plane Magnetization, and F is a Ni/[Co/Ni]n multilayer with out-of-plane Magnetization. The supercurrent in these junctions decays very slowly with F-layer thickness, and is much larger than in similar junctions not containing the two F' layers. Those two features are the characteristic signatures of spin-triplet supercurrent, which is maximized by the orthogonality of the Magnetizations in the F and F' layers. Magnetic measurements confirm the out-of-plane anisotropy of the Co/Ni multilayers. These samples have their critical current optimized in the as-prepared state, which will be useful for future applications.
A. K. Zvezdin - One of the best experts on this subject based on the ideXlab platform.
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high field anomalies of equilibrium and ultrafast magnetism in rare earth transition metal ferrimagnets
Physical Review B, 2019Co-Authors: A Tsukamoto, A. K. Zvezdin, Andrei Kirilyuk, Theo Rasing, A Pogrebna, K H Prabhakara, Margarita N Davydova, J BeckerAbstract:Magneto-optical spectroscopy in fields up to 30 T reveals anomalies in the equilibrium and ultrafast magnetic properties of the ferrimagnetic rare-earth--transition-metal alloy TbFeCo. In particular, near the Magnetization compensation temperature, each of the Magnetizations of the antiferromagnetically coupled Tb and FeCo sublattices show triple hysteresis loops. Contrary to state-of-the-art theory, which explains such loops by sample inhomogeneities, here we show that they are an intrinsic property of the rare-earth ferrimagnets. Assuming that the rare-earth ions are paramagnetic and have a nonzero orbital momentum in the ground state and, therefore, a large magnetic anisotropy, we are able to reproduce the experimentally observed behavior in equilibrium. The same theory is also able to describe the experimentally observed critical slowdown of the spin dynamics near the Magnetization compensation temperature, emphasizing the role played by the orbital momentum in static and ultrafast magnetism of ferrimagnets.
Reza Loloee - One of the best experts on this subject based on the ideXlab platform.
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spin triplet supercurrent in josephson junctions containing a synthetic antiferromagnet with perpendicular magnetic anisotropy
Physical Review B, 2017Co-Authors: Joseph A Glick, Reza Loloee, Norman O. Birge, W. P. Pratt, Samuel Edwards, Demet Korucu, Victor Aguilar, Bethany Niedzielski, Paul G KotulaAbstract:We present measurements of Josephson junctions containing three magnetic layers with noncolinear Magnetizations. The junctions are of the form $S/F^{\prime}/N/F/N/F^{\prime \prime}/S$, where $S$ is superconducting Nb, $F^\prime$ is either a thin Ni or Permalloy layer with in-plane Magnetization, $N$ is the normal metal Cu, $F$ is a synthetic antiferromagnet (SAF) with Magnetization perpendicular to the plane, composed of Pd/Co multilayers on either side of a thin Ru spacer, and $F^{\prime \prime}$ is a thin Ni layer with in-plane Magnetization. The supercurrent in these junctions decays more slowly as a function of the $F$-layer thickness than for similar spin-singlet junctions not containing the $F^\prime$ and $F^{\prime \prime}$ layers. The slower decay is the prime signature that the supercurrent in the central part of these junctions is carried by spin-triplet pairs. The junctions containing $F^{\prime}=$ Permalloy are suitable for future experiments where either the amplitude of the critical current or the ground-state phase difference across the junction is controlled by changing the relative orientations of the Magnetizations of the $F^{\prime}$ and $F^{\prime \prime}$ layers.
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spin triplet supercurrent in co ni multilayer josephson junctions with perpendicular anisotropy
Physical Review B, 2012Co-Authors: E C Gingrich, P Quarterman, Reza Loloee, W. P. Pratt, Yixing Wang, Norman O. BirgeAbstract:We have measured spin-triplet supercurrent in Josephson junctions of the form S/F'/F/F'/S, where S is superconducting Nb, F' is a thin Ni layer with in-plane Magnetization, and F is a Ni/[Co/Ni]n multilayer with out-of-plane Magnetization. The supercurrent in these junctions decays very slowly with F-layer thickness, and is much larger than in similar junctions not containing the two F' layers. Those two features are the characteristic signatures of spin-triplet supercurrent, which is maximized by the orthogonality of the Magnetizations in the F and F' layers. Magnetic measurements confirm the out-of-plane anisotropy of the Co/Ni multilayers. These samples have their critical current optimized in the as-prepared state, which will be useful for future applications.
Michael A. Susner - One of the best experts on this subject based on the ideXlab platform.
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the effect of chemical pressure on the structure and properties of a2croso6 a sr ca ferrimagnetic double perovskite
Journal of Solid State Chemistry, 2016Co-Authors: Ryan Morrow, Michael A. Susner, Michael D. Sumption, Jennifer R Soliz, Adam J Hauser, James C Gallagher, A A AczelAbstract:Abstract The ordered double perovskites Sr2CrOsO6 and Ca2CrOsO6 have been synthesized and characterized with neutron powder diffraction, electrical transport measurements, and high field Magnetization experiments. As reported previously Sr2CrOsO6 crystallizes with R 3 ¯ symmetry due to a−a−a− octahedral tilting. A decrease in the tolerance factor leads to a−a−b+ octahedral tilting and P21/n space group symmetry for Ca2CrOsO6. Both materials are found to be ferrimagnetic insulators with saturation Magnetizations near 0.2 μB. Sr2CrOsO6 orders at 660 K while Ca2CrOsO6 orders at 490 K. Variable temperature Magnetization measurements suggest that the Magnetization of the Cr3+ and Os3+ sublattices have different temperature dependences in Sr2CrOsO6. This leads to a non-monotonic temperature evolution of the magnetic moment. Similar behavior is not seen in Ca2CrOsO6. Both compounds have similar levels of Os/Cr antisite disorder, with order parameters of η=80.2(4)% for Sr2CrOsO6 and η=76.2(5)% for Ca2CrOsO6, where η=2θ−1 and θ is the occupancy of the osmium ion on the osmium-rich Wyckoff site.
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magnetic measurement of interstrand contact resistance and persistent current Magnetization of nb3sn rutherford cables with cores of mgo tape and woven s glass ribbon
ADVANCES IN CRYOGENIC ENGINEERING: Transactions of the International Cryogenic Materials Conference - ICMC Volume 58, 2012Co-Authors: Edward W. Collings, Daniel R. Dietderich, Michael A. Susner, Michael D. Sumption, Arend NijhuisAbstract:Rutherford cables exhibit two classes of parasitic Magnetization both of which can distort the bore-field of an accelerator magnet: (1) a static Magnetization ("hysteretic") resulting from intrastrand persistent currents, and (2) a dynamic Magnetization produced by interstrand coupling currents passing through interstrand contact resistances (ICR) during field ramping. Interstrand coupling can be controlled by a core placed between the layers of the cable. Stainless steel ribbon (with its associated native oxide coating) is a frequently used core. Recently, however, MgO-paper tapes and woven s-glass ribbons have been suggested as alternative core materials in the interests of improved flexibility and compatibility with the cabling process. Interstrand contact resistances can be extracted from the results of AC loss measurement. Accordingly pickup-coil Magnetization measurements of AC loss have been carried out on a group of cables with paper and ribbon cores. This paper reports on the resulting ICR results which it compares to those from uncored and stainless-steel-cored cables; it concludes by comparing the LHC-ramp-rate induced coupling Magnetization of a typical cored Nb3Sn Rutherford cable with its transport-current-moderated persistent-current Magnetizations at low and high fields.Rutherford cables exhibit two classes of parasitic Magnetization both of which can distort the bore-field of an accelerator magnet: (1) a static Magnetization ("hysteretic") resulting from intrastrand persistent currents, and (2) a dynamic Magnetization produced by interstrand coupling currents passing through interstrand contact resistances (ICR) during field ramping. Interstrand coupling can be controlled by a core placed between the layers of the cable. Stainless steel ribbon (with its associated native oxide coating) is a frequently used core. Recently, however, MgO-paper tapes and woven s-glass ribbons have been suggested as alternative core materials in the interests of improved flexibility and compatibility with the cabling process. Interstrand contact resistances can be extracted from the results of AC loss measurement. Accordingly pickup-coil Magnetization measurements of AC loss have been carried out on a group of cables with paper and ribbon cores. This paper reports on the resulting ICR result...
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coupling loss interstrand contact resistance and Magnetization of nb _ 3 sn rutherford cables with cores of mgo tape and s glass ribbon
IEEE Transactions on Applied Superconductivity, 2011Co-Authors: Edward W. Collings, Daniel R. Dietderich, Michael A. Susner, Michael D. Sumption, Arend NijhuisAbstract:Multistrand cables may exhibit two classes of parasitic Magnetization both of which can distort the bore-field of an accelerator magnet: (1) a static Magnetization (“hysteretic”) resulting from intrastrand persistent currents, and (2) a dynamic Magnetization produced by interstrand coupling currents generated during field ramping. The latter, which are moderated by the interstrand contact resistances (ICR), can be controlled by the presence of an insulating core inserted between the layers of the cable. Stainless steel ribbon (with its associated native oxide coating) is a frequently used core. Recently, however, MgO-paper tapes and woven s-glass ribbons have been suggested by LBNL (Lawrence Berkeley National Laboratory) as alternative core materials in the interests of improved flexibility and compatibility with the cabling process. This paper reports on the results of calorimetric AC loss (hence ICR) measurements on a set of four such cables and presents the results within the context of previously measured cored and uncored Nb3Sn cables. Also considered is a typical ramp-rate-induced coupling Magnetization and its relationship to persistent-current Magnetizations over the operating range of an accelerator magnet.
