Local density of states and order parameter configurations in layered ferromagnet-superconductor structures

Halterman, Klaus; Valls, Oriol T.

doi:10.1016/j.physc.2005.02.004

Cited by 7 publications

(6 citation statements)

References 28 publications

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“…In particular, the inversion of δν with increasing the thickness of the F layer d was observed. This effect has been explained theoretically in terms of the SR component oscillations in space [55,56,57,58].…”

Section: Dos In a Diffusive Sf Bilayermentioning

confidence: 99%

Odd triplet superconductivity in a superconductor/ferromagnet structure with a narrow domain wall

Volkov

Efetov

2008

Phys. Rev. B

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We study proximity effect in superconductor-ferromagnet (SF) structure with a narrow domain wall (DW) at the SF interface. The width of the domain wall is assumed to be larger than the Fermi wave length, but smaller than other characteristic lengths (for example, the "magnetic" length). The transmission coefficient is supposed to be small so that we deal with a weak proximity effect. Solving the linearized Eilenberger equation, we find analytical expressions for quasiclassical Green's functions. These functions describe the short-range (SR) condensate components, singlet and triplet with zero projection of the total spin on the quantization z-axis, induced in F due to the proximity effect as well as long-range odd triplet component (LRTC) with a nonzero projection of the total spin of Cooper pairs on the z-axis. The amplitude of the LRTC essentially depends on the product hτ and increases with increasing the exchange energy h (τ is the elastic scattering time). We calculate the Josephson current in SFS junction with a thickness of the F layer much greater than the penetration length of the SR components. The Josephson critical current caused by the LRTC may be both positive and negative depending on chirality of the magnetic structure in F.The density of states (DOS) in a diffusive SF bilayer is also analyzed. It is shown that the contributions of the SR and LR components to the DOS in F have a different dependence on the thickness d of the F layer (nonmonotonous and monotonous).

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Section: Dos In a Diffusive Sf Bilayermentioning

confidence: 99%

Odd triplet superconductivity in a superconductor/ferromagnet structure with a narrow domain wall

Volkov

Efetov

2008

Phys. Rev. B

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“…The amplitudes of the opposite-spin correlations pervading the adjacent ferromagnet, undergo damped oscillations as a function of position which reveals itself in 0-π transitions of the supercurrent. 1,[7][8][9][10] Since about a decade ago, several proposals have been put forth to achieve attainable and practical platforms that isolate and utilize the proximity-induced 3,4 superconducting triplet correlations in SF hybrids. 1,2 The signatures of the proximity-induced electronic density of states (DOS) in the F layers of these hybrid structures can reveal the existence and type of superconducting correlations in the region.…”

Section: Introductionmentioning

confidence: 99%

“…1,2 The signatures of the proximity-induced electronic density of states (DOS) in the F layers of these hybrid structures can reveal the existence and type of superconducting correlations in the region. [9][10][11][12][13] One promising prospect for unambiguously detecting triplet correlations experimentally involves tunneling spectroscopy experiments which can probe the local single particle spectra encompassing the proximityinduced DOS. 11,12,[14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Nonetheless, competing effects can make analysis of the results of such a 'direct' probe of spintriplet superconducting correlations problematic.…”

Section: Introductionmentioning

confidence: 99%

Zero-energy peak and triplet correlations in nanoscale superconductor/ferromagnet/ferromagnet spin valves

2015

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Using a self-consistent Bogoliubov-de Gennes approach, we theoretically study the proximity-induced density of states (DOS) in clean SF F spin-valves with noncollinear exchange fields. Our results clearly demonstrate a direct correlation between the presence of a zero energy peak (ZEP) in the DOS spectrum and the persistence of spin-1 triplet pair correlations. By systematically varying the geometrical and material parameters governing the spin-valve, we point out to experimentally optimal system configurations where the ZEPs are most pronounced, and which can be effectively probed via scanning tunneling microscopy. We complement these findings in the ballistic regime by employing the Usadel formalism in the full proximity limit to investigate their diffusive SF F counterparts. We determine the optimal normalized ferromagnetic layer thicknesses which result in the largest ZEPs. Our results can serve as guidelines in designing samples for future experiments.

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“…Ballistic SF structures with a nonhomogeneous magnetization, where the LRTC could be created, were studied in Refs. [24][25][26][27] . The papers [28][29][30][31] were devoted to the study of the LRTC in spiral ferromagnets attached to superconductors.…”

Section: Introductionmentioning

confidence: 99%

Odd spin-triplet superconductivity in a multilayered superconductor-ferromagnet Josephson junction

Volkov

Efetov

2010

Phys. Rev. B

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We study the dc Josephson effect in a diffusive multilayered SF'FF'S structure, where S is a superconductor and F,F' are different ferromagnets. We assume that the exchange energies in the F' and F layers are different (h and H, respectively) and the middle F layer consists of two layers with parallel or antiparallel magnetization vectors M . The M vectors in the left and right F' layers are generally not collinear to those in the F layer. In the limit of a weak proximity effect we use a linearized Usadel equation. Solving this equation, we calculate the Josephson critical current for arbitrary temperatures, arbitrary thicknesses of the F' and F layers (L h and LH ) in the case of parallel and antiparallel M orientations in the F layer. The part of the critical current IcSR formed by the short-range (SRC) singlet and S = 0 triplet condensate components decays on a short length ξH = D/H , whereas the part IcLR due to the long-range triplet |S| = 1 component (LRTC) decreases with increasing LH on the length ξN = D/πT . Our results are in a qualitative agreement with the experiment 36 .

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Local density of states and order parameter configurations in layered ferromagnet-superconductor structures

Cited by 7 publications

References 28 publications

Odd triplet superconductivity in a superconductor/ferromagnet structure with a narrow domain wall

Odd triplet superconductivity in a superconductor/ferromagnet structure with a narrow domain wall

Zero-energy peak and triplet correlations in nanoscale superconductor/ferromagnet/ferromagnet spin valves

Odd spin-triplet superconductivity in a multilayered superconductor-ferromagnet Josephson junction

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