Non-Fraunhofer Interference Pattern in Inhomogeneous Ferromagnetic Josephson Junctions

Alidoust, Mohammad; Sewell, Granville; Linder, Jacob

doi:10.1103/physrevlett.108.037001

Cited by 21 publications

(40 citation statements)

References 32 publications

(24 reference statements)

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“…It is known that the linear arrangement of the vortices along the superconducting interface is modified by insulating boundaries [9][10][11][12], in a junction of lateral width W comparable to the separation L of the interfaces. But in wide junctions (W L), when boundary effects are irrelevant, only linear arrangements of Josephson vortices are known [13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional Josephson vortex lattice and anomalously slow decay of the Fraunhofer oscillations in a ballistic SNS junction with a warped Fermi surface

et al. 2016

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The critical current of a Josephson junction is an oscillatory function of the enclosed magnetic flux , because of quantum interference modulated with periodicity h/2e. We calculate these Fraunhofer oscillations in a two-dimensional (2D) ballistic superconductor-normal-metal-superconductor (SNS) junction. For a Fermi circle the amplitude of the oscillations decays as 1/ or faster. If the Fermi circle is strongly warped, as it is on a square lattice near the band center, we find that the amplitude decays slower, ∝1/ √ , when the magnetic length l m = √ /eB drops below the separation L of the NS interfaces. The crossover to the slow decay of the critical current is accompanied by the appearance of a 2D array of current vortices and antivortices in the normal region, which form a bipartite rectangular lattice with lattice constant l 2 m /L. The 2D lattice vanishes for a circular Fermi surface, when only the usual single row of Josephson vortices remains.

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Section: Introductionmentioning

confidence: 99%

Two-dimensional Josephson vortex lattice and anomalously slow decay of the Fraunhofer oscillations in a ballistic SNS junction with a warped Fermi surface

et al. 2016

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“…7 Our general analytical and numerical framework permits the study of magnetization textures with highly intricate patterns. 72,73 Our methodology also allows for rather general geometric parameters, including arbitrary ratios of the side lengths describing the ferromagnet strips. We first consider a S/F /S Josephson junction with a uniform magnetization texture, thus extending the results of a normal S/N /S Josephson junction.…”

Section: Introductionmentioning

confidence: 99%

Proximity induced vortices and long-range triplet supercurrents in ferromagnetic Josephson junctions and spin valves

Alidoust

Halterman

2015

Journal of Applied Physics

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Using a spin-parameterized quasiclassical Keldysh-Usadel technique, we theoretically study supercurrent transport in several types of diffusive ferromagnetic(F )/superconducting(S) configurations with differing magnetization textures. We separate out the even-and odd-frequency components of the supercurrent within the low proximity limit and identify the relative contributions from the singlet and triplet channels. We first consider inhomogeneous one-dimensional Josephson structures consisting of a uniform bilayer magnetic S/F /F /S structure and a trilayer S/F /F /F /S configuration, in which case the outer F layers can have either a uniform or conical texture relative to the central uniform F layer. Our results demonstrate that for supercurrents flowing perpendicular to the F /F interfaces, incorporating a conical texture yields the most effective way to observe the signatures of the long-ranged spin-triplet supercurrents. We also consider three different types of finitesized two-dimensional magnetic structures subjected to an applied magnetic field normal to the junction plane: a S/F /S junction with uniform magnetization texture, and two S/F /F /S configurations with differing F /F bilayer arrangements. In one case, the F /F interface is parallel with the S/F junction interfaces while in the other case, the F /F junction is oriented perpendicular to the S/F interfaces. We then discuss the proximity vortices and corresponding spatial maps of currents inside the junctions. For the uniform S/F /S junction, we analytically calculate the magnetic field induced supercurrent and pair potential in both the narrow and wide junction regimes, thus providing insight into the variations in the Fraunhofer diffraction patterns and proximity vortices when transitioning from a wide junction to a narrow one. Our extensive computations demonstrate that the induced long-range spin-triplet supercurrents can deeply penetrate uniform F /F bilayers when spin-singlet supercurrents flow parallel to the F /F interfaces. This is in stark contrast to configurations where a spin-singlet supercurrent flows perpendicular to the F /F interfaces. We pinpoint the origin of the induced triplet and singlet correlations through spatial profiles of the decomposed total supercurrents. We find that the penetration of the long-range spin-triplet supercurrents associated with supercurrents flowing parallel to the F /F interfaces, are more pronounced when the thickness of the F strips are unequal. Lastly, if one of the S terminals is replaced with a finite-sized normal metal, we demonstrate that the corresponding experimentally accessible S/F /F /N spin valve presents an effective platform in which the predicted long-range effects can be effectively generated and probed.

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“…1(c), permits experimental isolation of the long-range triplets and confirmation of this generic effect. A general three-dimensional quasiclassical formalism for diffusive magnetic heterostructures subject to an external magnetic field is described by the following Usadel equations [15][16][17]: interfaces. The ferromagnetic layers, F1 and F2 have uniform magnetizations and N represents a nonmagnetic normal metal with a finite thickness dN .…”

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confidence: 99%

“…τ . We denote the diffusion constant of the medium by D andǦ, h are functions of coordinates r≡(x, y, z) [15,16]. Here, the exchange field describing the ferromagnetic region, h(r)=(h x (r), h y (r), h z (r)), can take arbitrary directions.…”

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Long-range triplet supercurrents induced by singlet supercurrents parallel to magnetic interfaces

Alidoust

Halterman

2014

Applied Physics Letters

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Non-Fraunhofer Interference Pattern in Inhomogeneous Ferromagnetic Josephson Junctions

Cited by 21 publications

References 32 publications

Two-dimensional Josephson vortex lattice and anomalously slow decay of the Fraunhofer oscillations in a ballistic SNS junction with a warped Fermi surface

Two-dimensional Josephson vortex lattice and anomalously slow decay of the Fraunhofer oscillations in a ballistic SNS junction with a warped Fermi surface

Proximity induced vortices and long-range triplet supercurrents in ferromagnetic Josephson junctions and spin valves

Long-range triplet supercurrents induced by singlet supercurrents parallel to magnetic interfaces

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