Magnetic interference patterns in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mn>0</mml:mn><mml:mtext>−</mml:mtext><mml:mi>π</mml:mi></mml:mrow></mml:math>superconductor/insulator/ferromagnet/superconductor Josephson junctions: Effects of asymmetry between 0 and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>π</mml:mi></mml:math>regions

Kemmler, M.; Weides, Martin; Weiler, Mathias; Opel, Matthias; Goennenwein, Sebastian T. B.; Vasenko, A. S.; Golubov, Alexandre Avraamovitch; Kohlstedt, H.; Koelle, D.; Kleiner, R.; Goldobin, E.

doi:10.1103/physrevb.81.054522

Cited by 58 publications

(59 citation statements)

References 36 publications

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“…This effect, which is not reproduced by the simulated curve, is due to the finite magnetization of the F-layer which, in addition, is different in the 0 and π parts. This effect is addressed elsewhere [48].…”

Section: -π Josephson Junctionmentioning

confidence: 95%

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

et al. 2010

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Josephson junctions with ferromagnetic barrier can have positive or negative critical current depending on the thickness d F of the ferromagnetic layer. Accordingly, the Josephson phase in the ground state is equal to 0 (a conventional or 0 junction) or to π (π junction). When 0 and π segments are joined to form a "0-π junction", spontaneous supercurrents around the 0-π boundary can appear. Here we report on the visualization of supercurrents in superconductor-insulatorferromagnet-superconductor (SIFS) junctions by low-temperature scanning electron microscopy (LTSEM). We discuss data for rectangular 0, π, 0-π, 0-π-0 and 20 × (0-π-) junctions, disk-shaped junctions where the 0-π boundary forms a ring, and an annular junction with two 0-π boundaries.Within each 0 or π segment the critical current density is fairly homogeneous, as indicated both by measurements of the magnetic field dependence of the critical current and by LTSEM. The π parts have critical current densities j π c up to 35 A/cm 2 at T = 4.2 K, which is a record value for SIFS junctions with a NiCu F-layer so far. We also demonstrate that SIFS technology is capable to produce Josephson devices with a unique topology of the 0-π boundary.

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Section: -π Josephson Junctionmentioning

confidence: 95%

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

et al. 2010

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“…Due to the skyrmion magnetization texture varying along the y-axis, the present junction may be regarded as a parallel circuit of 0 and π junctions. In such a circuit of 0 and π junctions, a local minimum at Φ = 0 can appear due to the cancellation of the Josephson currents from the 0 and π segments 46 . In this way, the Fraunhofer pattern in our setup can display a local minimum at zero flux near the 0-π transition points.…”

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confidence: 99%

Josephson effect through magnetic skyrmions

Yokoyama

Linder

2015

Phys. Rev. B

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We discover that the multiple degrees of freedom associated with magnetic skyrmions: size, position, and helicity, can all be used to control the Josephson effect and 0-π transitions occurring in superconductor/magnetic skyrmion/superconductor junctions. In the presence of two skyrmions, the Josephson effect depends strongly on their relative helicity and leads to the possibility of a helicity-transistor effect for the supercurrent where the critical current is changed by several orders of magnitude simply by reversing the helicity of a magnetic skyrmion. Moreover, we demonstrate that the Fraunhofer pattern can show a local minimum at zero flux as a direct result of the skyrmion magnetic texture. These findings demonstrate the rich physics that emerges when combining topological magnetic objects with superconductors and could lead to new perspectives in superconducting spintronics. PACS numbers: 73.43.Nq, 72.25.Dc, The interplay between superconductivity and ferromagnetism in hybrid structures has received much attention in recent years 1,2 , due to its allure from a fundamental physics viewpoint and also because of improved and new functionality brought about by using superconductors in spintronics 3 . Due to the proximity effect, the Cooper pairs induced in the ferromagnet acquire a finite center of mass momentum. Therefore, the pair amplitude oscillates in space which may result in a sign change of the Josephson current in ferromagnetic Josephson junctions. This effect can be used to control the quantum ground state of the system, altering from a state where the superconducting phase difference is 0 to a state where it is π 4-7 . This 0-π transition was originally observed in Josephson junctions through weak ferromagnets. 8,9 Also, in the presence of inhomogeneity of the magnetic order, triplet pairing with spin aligned with the local exchange field is generated in the ferromagnet due to spin flip scattering 10,11 . Experiments have successfully demonstrated the presence of such spin-triplet pairing by observing a Josephson current through strong ferromagnets [12][13][14] , which can be explained via the concepts of spin-mixing and spinrotation taking place near the superconductor/ferromagnet interface 15 . Using equal spin triplet pairings, the possibility arises to enhance existing effects or discover new ones in spintronics 3,[16][17][18][19][20] . Recently, it has been also proposed that inhomogeneous ferromagnet/superconductor junctions can create topological superconductivity. [21][22][23] Currently, much interest is garnered by magnetic skyrmions in chiral magnets [24][25][26] . Such objects are characterized by a topologically protected spin configuration. Due to their peculiar magnetic structure, several intriguing phenomena have been discovered such as topological and skyrmion Hall effects 27-29 and current-driven motion of skyrmion with ultralow current density [30][31][32][33][34] . It has been shown that magnetic skyrmions can be also driven by a temperature gradient [35][36][37][38] . A thermal ...

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“…Due to the proximity effect between S and F in a S/F junction, the spin-singlet Cooper pairs (SSCs) penetrate into the F and acquire a finite center-of-mass momentum proportional to the exchange splitting between up-and down-spin bands in the F. The pair amplitude of SSC shows damped oscillation with increasing the thickness of F. One interesting phenomena induced by the damped oscillatory behavior of the pair amplitude of SSC is a π-state in a S/F/S junction, where the current-phase relation in the Josephson junction is shifted by π from that of the ordinary S/I/S or S/N/S junction (called 0-state) [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. It is expected that the π-state can be utilized for an element of quantum computing and circuit [24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Magnetization induced by odd-frequency spin-triplet Cooper pairs in a Josephson junction with metallic trilayers

Hikino

Yunoki

2015

Phys. Rev. B

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We theoretically study the magnetization inside a normal metal induced in an s-wave superconductor/ferromagnetic metal/normal metal/ferromagnetic metal/s-wave superconductor (S/F1/N/F2/S) Josephson junction. Using the quasiclassical Green's function method, we show that the magnetization becomes finite inside the N . The origin of this magnetization is due to odd-frequency spin-triplet Cooper pairs formed by electrons of equal and opposite spins, which are induced by the proximity effect in the S/F1/N/F2/S junction. We find that the magnetiza-, where θ is the superconducting phase difference between the two Ss and d is the thickness of N . The θ independent magnetization M I (d) exists generally in S/F junctions, while M II (d, θ) carries all θ dependence and represents the fingerprint of the phase coherence between the two Ss in Josephson junctions. The θ dependence thus allows us to control the magnetization in the N by tuning θ for a fixed d. We show that the θ independent magnetization M I (d) weakly decreases with increasing d, while the θ dependent magnetization M II (d, θ) rapidly decays with d. Moreover, we find that the time-averaged magnetization M II (d, θ) exhibits a discontinuous peak at each resonance DC voltage Vn = n ωS/2e (n: integer) when DC voltage V as well as AC voltage vac(t) with frequency ωS are both applied to the S/F1/N/F2/S junction. This is because M II (d, θ) oscillates generally in time t (AC magnetization) with dθ/dt = 2e[V + vac(t)]/ and thus M II (d, θ) = 0, but can be converted into the time-independent DC magnetization for the DC voltage at Vn. We also discuss that the magnetization induced in the N can be measurably large in realistic systems. Therefore, the measurement of the induced magnetization serves as an alternative way to detect the phase coherence between the two Ss in Josephson junctions. Our results also provide a basic concept for tunable magnetization in superconducting spintronics devices.

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Magnetic interference patterns in0−πsuperconductor/insulator/ferromagnet/superconductor Josephson junctions: Effects of asymmetry between 0 andπregions

Cited by 58 publications

References 36 publications

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

Visualizing supercurrents in ferromagnetic Josephson junctions with various arrangements of 0 andπsegments

Josephson effect through magnetic skyrmions

Magnetization induced by odd-frequency spin-triplet Cooper pairs in a Josephson junction with metallic trilayers

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