Spontaneous Helical Order of a Chiral 
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-Wave Superfluid Confined in Nanoscale Channels

Wiman, Joshua; Sauls, J. A.

doi:10.1103/physrevlett.121.045301

Cited by 15 publications

(44 citation statements)

References 22 publications

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“…Recent work by the Northwestern University theory group has shown that in the Ginzburg-Landau regime the strong-coupling effects in 3 He do not eliminate the stripe state in film geometry [68]. They also have found a similar instability towards formation of periodic order in two-dimensional strips of chiral p-wave state xpx + i ypy [69] and new superfluid phases that spontaneously break rotational and translational symmetries in cylindrical channels [70].…”

Section: (C) Other Geometries Pairing States and Effects Of Competing Interactions And Boundary Conditionsmentioning

confidence: 99%

Andreev bound states in superconducting films and confined superfluid ³ He

Vorontsov

2018

Phil. Trans. R. Soc. A.

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This paper reviews confinement-driven phase transitions in superconductors and Bardeen-Cooper-Schrieffer superfluids, and the appearance in thin films of new phases that break the time-reversal or translational symmetry. The origins of the new phases are closely tied to the Andreev scattering processes involving particle-hole conversions that create surface quasiparticle states with energies inside the superconducting gap. Restructuring of the low-energy spectrum in the surface region of several coherence lengths results in large spatial variations of the superconducting order parameter. In confined geometry, such as slabs, films, pores or nano-dots, with one or more physical dimensions∼10, the Andreev bound states can dominate properties of a superconductor, leading to modified experimental signatures. They can significantly change the energy landscape, and drive transitions into new superconducting phases. The new phases are expected in a variety of materials, from singlet -wave superconductors to multi-component triplet superfluidHe, but properties of the new phases will depend on the symmetry of the parent state. I will highlight the connection between the Andreev surface states and confinement-stabilized phases with additional broken symmetries, describe recent progress and open questions in the theoretical and experimental investigation of superfluids in confined geometry.This article is part of the theme issue 'Andreev bound states'.

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Section: (C) Other Geometries Pairing States and Effects Of Competing Interactions And Boundary Conditionsmentioning

confidence: 99%

Andreev bound states in superconducting films and confined superfluid ³ He

Vorontsov

2018

Phil. Trans. R. Soc. A.

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“…Even though the spin-triplet superfluity in 3 He has been studied for many years, the Eilenberger-type free-energy expression is derived only in the present paper, advancing the theory of spintriplet paired states. This tool should be particularly useful to study different competing and spatially inhomogeneous phases for the confined topological superfluids [6,44,63,64], exotic disordered phases [65,66], and vortex states, such as double-core vortices [67][68][69][70][71][72][73][74] and recently found halfquantum vortices [75,76]. We now derive Eq.…”

Section: Summary and Discussionmentioning

confidence: 99%

Quasiclassical free energy of superconductors: Disorder-driven first-order phase transition in superconductor/ferromagnetic-insulator bilayers

2020

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In the seminal work by G. Eilenberger, Z. Phys. 214, 195 (1968), a closed-form expression for the free energy of inhomogeneous spin-singlet superconductor in terms of quasiclassical propagators has been suggested. However, deriving this expression and generalizing it for superconductors or superfluids with general matrix structure, e.g., spin-triplet correlations, has remained problematic. Starting from the Luttinger-Ward formulation, we discuss here the general solution. Besides ordinary superconductors with various scattering mechanisms, the obtained free-energy functional can be used for systems, such as superfluid 3 He and superconducting systems with spatially inhomogeneous exchange field or spin-orbit coupling. Using this result, we derive the simplified expression for the free energy in the diffusive and hydrodynamic limits. As an example of using this formalism, we show that impurity scattering restores the first-order phase transition in superconductor-ferromagnetic insulator bilayers making this system similar to the bulk superconductor with the homogeneous built-in exchange field.

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“…In parallel to the various experimental developments the modeling of the various superfluid phases in an anisotropic aerogel has been advanced [16][17][18]. In addition, it had been shown previously that the polar phase could be stable in anisotropic aerogels [19] and channels [20]. Quite recently an experimental/theoretical cooperation has elucidated in detail [7,21] the important role played by half-quantum vortices and walls in the polar and the distorted phases of superfluid 3 He.…”

Section: Introductionmentioning

confidence: 99%

Macroscopic behavior of the distorted A and B phases and the polar phase of superfluid He3 in an anisotropic aerogel

Brand

Pleiner

2020

Phys. Rev. B

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We describe the macroscopic behavior of superfluid 3 He in the polar and the distorted A and B phases in an anisotropic aerogel. It turns out that the distorted A phase shares many features with superfluid 3 He-A. Its order parameter contains the polar phase as well as the A phase as a smooth limiting case. The former is in agreement with the fact that the phase transition polar to distorted A is observed to be of second order. Due to the different structure of the order parameter, the unit vectorl, which is characteristic of the superfluid 3 He-A and the distorted A phase, is not present in the polar phase. As new macroscopic variables compared to superfluid 3 He we have for the superfluid distorted A phase in an aerogel the strain field associated with the aerogel network. In addition, we have in superfluid 3 He relative rotations between the anisotropic gel network and thel vector as a macroscopic variable. As a result of these additional macroscopic variables we find new static and dynamic crosscoupling terms, which come as reversible (zero entropy production) as well as as irreversible contributions. The polar phase in an anisotropic aerogel is anisotropic in its elastic properties. We have as additional macroscopic variables relative rotations similar to those of a nematic liquid crystalline elastomer, since the preferred direction in the polar phase is even under time reversal and not odd as for the distorted A phase. These additional features lead to static and dissipative cross-coupling terms, which cannot exist for a polar phase in an isotropic aerogel. For the distorted B phase we find for the orbital part a macroscopic dynamic behavior which shares some features with that of the polar phase. In contrast to the polar phase, however, the distorted B phase does not show relative rotations, since there is only one preferred direction. The preferred direction in the distorted B phase leads to a preferred direction in spin space as well. As a consequence the spin waves become anisotropic and longitudinal and transverse spin waves become coupled, even in the absence of a magnetic field. We also discuss briefly the coupling to the spin degrees of freedom in the polar and the distorted A phase.

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Spontaneous Helical Order of a Chiral p -Wave Superfluid Confined in Nanoscale Channels

Cited by 15 publications

References 22 publications

Andreev bound states in superconducting films and confined superfluid ³ He

Andreev bound states in superconducting films and confined superfluid ³ He

Quasiclassical free energy of superconductors: Disorder-driven first-order phase transition in superconductor/ferromagnetic-insulator bilayers

Macroscopic behavior of the distorted A and B phases and the polar phase of superfluid He3 in an anisotropic aerogel

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Spontaneous Helical Order of a Chiral p -Wave Superfluid Confined in Nanoscale Channels

Cited by 15 publications

References 22 publications

Andreev bound states in superconducting films and confined superfluid 3 He

Andreev bound states in superconducting films and confined superfluid 3 He

Quasiclassical free energy of superconductors: Disorder-driven first-order phase transition in superconductor/ferromagnetic-insulator bilayers

Macroscopic behavior of the distorted A and B phases and the polar phase of superfluid He3 in an anisotropic aerogel

Contact Info

Product

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Andreev bound states in superconducting films and confined superfluid ³ He

Andreev bound states in superconducting films and confined superfluid ³ He