Direct Imaging of Integer and Half-Integer Josephson Vortices in High-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>T</mml:mi></mml:mrow><mml:mrow><mml:mi>c</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math>Grain Boundaries

Kirtley, J. R.; Tsuei, C. C.; Rupp, M.; Sun, Jian; Yu-Jahnes, Lock See; Gupta, A.; Ketchen, M. B.; Moler, Kathryn A.; Bhushan, M.

doi:10.1103/physrevlett.76.1336

Cited by 235 publications

(133 citation statements)

References 25 publications

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“…The presence of SFs was demonstrated experimentally 15 by scanning SQUID microscopy on YBa 2 Cu 3 O 7 -Nb ramp zigzag LJJs in the long facet limit, i.e., when the length of the facets a ≫ λ J . SFs were also experimentally observed in the tri-crystal grain boundary LJJs 16,17,18 In this work we study analytically the ground states of 0-π-LJJ with arbitrary number of alternating 0 and π facets and the effect of edge facets on the type of the ground state. As it was shown earlier for some particular cases, there is a critical facet length a c which separates the domains with the two most natural lowest energy configurations: the flat phase state and antiferromagnetically (AFM) ordered array of semifluxons.…”

Section: Introductionmentioning

confidence: 99%

Analysis of ground states of0−πlong Josephson junctions

Zenchuk

Goldobin

2004

Phys. Rev. B

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We investigate analytically a long Josephson 0-π-junction with several 0 and π facets which are comparable to the Josephson penetration length λJ . Such junctions can be fabricated exploiting (a) the d-wave order parameter symmetry of cuprate superconductors; (b) the spacial oscillations of the order parameter in superconductor-insulator-ferromagnet-superconductor structures with different thicknesses of ferromagnetic layer to produce 0 or π coupling or (c) the structure of the corresponding sine-Gordon equations and substituting the phase π-discontinuities by the artificial current injectors. We investigate analytically the possible ground states in such a system and show that there is a critical facet length ac, which separates the states with half-integer flux quanta (semifluxons) from the trivial "flat phase state" without magnetic flux. We analyze different branches of the bifurcation diagram, derive a system of transcendental equations which can be effectively solved to find the crossover distance ac (bifurcation point) and present the solutions for different number of facets and the edge facets length. We show that the edge facets may drastically affect the state of the system.

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Section: Introductionmentioning

confidence: 99%

Analysis of ground states of0−πlong Josephson junctions

Zenchuk

Goldobin

2004

Phys. Rev. B

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“…Convincing experimental evidence of HQVs was recently provided in a spinor polariton condensate 24 , where the properties of the system allow for direct imaging of both the amplitude and phase of the condensate wave function. Signs of fractional vorticity were previously only reported in hightemperature superconductors 25 , later indirectly measured in spin-triplet superconductors 26 and identified as a result of the decay of 2D Skyrmions in atomic condensates 27 , while their observation is still elusive in other spinor systems like He3 thin films 28 . Spin vortices and textures, which are closely related phenomena to HQVs, have been also investigated in ferromagnetic BEC of 87 Rb atoms 29 , opening the way to an even broader interest in spinor topologies.…”

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confidence: 99%

Dissociation dynamics of singly charged vortices into half-quantum vortex pairs

et al. 2012

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The quest for identification and understanding of fractional vorticity is a major subject of research in the quantum fluids domain, ranging from superconductors, superfluid Helium-3 to cold atoms. In a two-dimensional Bose degenerate gas with a spin degree of freedom, the fundamental topological excitations are fractional vortical entities, called half-quantum vortices. Convincing evidence for the existence of half-quantum vortices was recently provided in spinor polariton condensates. The half-quantum vortices can be regarded as the fundamental structural components of singly charged vortices but, so far, no experimental evidence of this relation has been provided. Here we report on the direct and time-resolved observation of the dynamical process of the dissociation of a singly charged vortex into its primary components, a pair of half-quantum vortices. The physical origin of the observed phenomenology is found in a spatially inhomogeneous static potential that couples the two spin components of the condensate.

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“…7,8 Such semifluxons were observed experimentally. 9,10,11,12,13 In contrast to an integer Josephson vortex (fluxon), which is a free moving soliton, a semifluxon is like a spin 1 2 particle -it is pinned at a 0-π boundary, has one of two possible polarities ± 1 2 Φ 0 and, the most important, can form the groundstate of the system. Semifluxons are very interesting non-linear objects: they can form a variety of groundstates, 14,15,16,17,18 may flip, 9,11,19 rearrange 15 or get depinned 17,20,21 by a bias current, lead to half-integer zero-field steps 20,21,22 and have a characteristic eigenfrequency.…”

Section: Introductionmentioning

confidence: 99%

Nonideal artificial phase discontinuity in long Josephson0−κjunctions

et al. 2005

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We investigate the creation of an arbitrary κ-discontinuity of the Josephson phase in a long NbAlOx-Nb Josephson junction (LJJ) using a pair of tiny current injectors, and study the formation of fractional vortices formed at this discontinuity. The current Iinj, flowing from one injector to the other, creates a phase discontinuity κ ∝ Iinj. The calibration of injectors is discussed in detail. The small but finite size of injectors leads to some deviations of the properties of such a 0-κ-LJJ from the properties of a LJJ with an ideal κ-discontinuity. These experimentally observed deviations in the dependence of the critical current on Iinj and magnetic field can be well reproduced by numerical simulation assuming a finite injector size. The physical origin of these deviations is discussed.

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Direct Imaging of Integer and Half-Integer Josephson Vortices in High-TcGrain Boundaries

Cited by 235 publications

References 25 publications

Analysis of ground states of0−πlong Josephson junctions

Analysis of ground states of0−πlong Josephson junctions

Dissociation dynamics of singly charged vortices into half-quantum vortex pairs

Nonideal artificial phase discontinuity in long Josephson0−κjunctions

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