Transition temperatures of superconductor-ferromagnet superlattices

Radović, Z.; Ledvij, M.; Dobrosavljević-Grujić, Ljiljana; Buzdin, Alexandre I.; Clem, John R.

doi:10.1103/physrevb.44.759

Cited by 352 publications

(281 citation statements)

References 17 publications

Supporting

Mentioning

260

Contrasting

Order By: Relevance

“…16 The model can be easily adapted to the S/F case by noting that the coherence length in the F metal is determined by ⌬E ex and therefore independent of temperature. [4][5][6] In an earlier analysis of results on V/Fe multilayers 9,10 a similar model was used ͑due to Radović et al 4 ͒, which could well describe the behavior of critical temperatures and critical fields, but did not incorporate interface transparency explicitly. As a matter of fact, the single parameter ⑀ of that model is, in general, not suited to describe proximity effect and transparency in an independent way, although it turns out to be possible in the limiting case of F/S/F trilayers with d F ӷ F .…”

Section: A Theory; a Brief Descriptionmentioning

confidence: 99%

“…͑A9͔͒ becomes ␥/(1ϩ␥ b ), i.e., the transparency can be incorporated in a single parameter. It is then possible to find the correspondence between this single parameter and the parameter ⑀ from the model of Radović et al, 4 defined as ⑀ϭ S…”

Section: ͑A11͒mentioning

confidence: 99%

“…2 Another is the possibility of a phase difference ⌬ ϭ over an S/F/S junction, 3 resulting in an oscillatory behavior of the superconducting transition temperature T c with F-layer thickness d F of S/F multilayers. [4][5][6] An oscillation in T c was recently reported for Nb/Gd, 7 but its origin is still controversial. 8 All such effects concern the behavior of the superconducting order parameter near the S/F interface, and in that sense they form part of the general issue of the proximity effect, well known for the S/N case, but hardly investigated for the S/F case.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Interface transparency of superconductor/ferromagnetic multilayers

et al. 1997

View full text Add to dashboard Cite

Interface transparency of superconductor/ferromagnetic multilayersAarts, J.; Geers, J.M.E.; Bruck, E.H.; Golubov, A.A.; Coehoorn, R.; Olsovec, M. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. We have investigated the behavior of the superconducting transition temperature T c in superconducting/ ferromagnetic ͑S/F͒ multilayers, as a function of the different layer thicknesses and for varying magnetic moment F of the F-layer atoms. The system studied consists of superconducting V and ferromagnetic V 1Ϫx Fe x alloys with x such that F on the Fe atom is varied between 2 and 0.25 B . We determined the superconducting coherence length in the F layer F , which is found to be inversely proportional to F . We also determined the critical thickness of the S layer, above which superconductivity appears. This thickness is found to be strongly nonmonotonic as function of the Fe concentration in the alloys. By analyzing the data in terms of the proximity-effect theory, we show that with increasing F , the increasing pair breaking in the F layer by the exchange field is counteracted by a decreasing transparency of the S/F interface for Cooper pairs.

show abstract

Section: A Theory; a Brief Descriptionmentioning

confidence: 99%

Section: ͑A11͒mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Interface transparency of superconductor/ferromagnetic multilayers

et al. 1997

View full text Add to dashboard Cite

show abstract

“…The occurrence of the π-phase shift makes it possible to realize the SFS π -junctions 1 , as was confirmed experimentally 4,5,6,7,8 . The order parameter oscillations also lead to nonmonotonous dependence of T c in SF bilayers on the F-layer thickness 9,10,11,12,13 . Effects of resonant transmission in conductivity of SF structures were discussed in Ref 14,15,16 .…”

mentioning

confidence: 99%

Resonant peak in the density of states in normal-metal/diffusive-ferromagnet/superconductor junctions

2005

View full text Add to dashboard Cite

The conditions for the formation of zero-energy peak in the density of states (DOS) in the normal metal / insulator / diffusive ferromagnet / insulator / s-wave superconductor (N/I/DF/I/S) junctions are studied by solving the Usadel equations. The DOS of the DF is calculated in various regimes for different magnitudes of the resistance, Thouless energy and the exchange field of the DF, as well as for various resistances of the insulating barriers. The conditions for the DOS peak are formulated for the cases of weak proximity effect (large resistance of the DF/S interface) and strong proximity effect (small resistance of the DF/S interface).In ferromagnet/superconductor (F/S) junctions Cooper pairs penetrating into the F layer from the S layer have a nonzero momentum due to the influence of exchange field 1,2,3 . This results in oscillating behavior of the pair amplitude or a π-phase shift of the order parameter in the ferromagnet. A negative sign of the real part of the order parameter may occur when the thickness of the F layer is larger than the coherence length of the F layer. The occurrence of the π-phase shift makes it possible to realize the SFS π -junctions 1 , as was confirmed experimentally 4,5,6,7,8 . The order parameter oscillations also lead to nonmonotonous dependence of T c in SF bilayers on the F-layer thickness 9,10,11,12,13 . Effects of resonant transmission in conductivity of SF structures were discussed in Ref 14,15,16 .Another interesting consequence of the oscillations of the pair amplitude is the spatially damped oscillating behavior of the density of states (DOS) in a ferromagnet predicted theoretically 17,18,19,20 in various regimes. The energy dependent DOS calculated in the clean 18 and the dirty 21 limits exhibits rich structures. Experimentally DOS in F/S bilayers was measured by Kontos et al. who found a broad DOS peak around zero energy when the π-phase shift occurs 22 . In diffusive ferromagnet/superconductor (DF/S) junctions the zeroenergy DOS may have a sharp peak 21 . However the conditions for the appearance of such anomaly have not been studied systematically so far.The purpose of the present paper is to calculate DOS in N/DF/S junctions and to formulate the conditions for the zero-energy DOS peak in two regimes corresponding to the weak proximity effect (large DF/S interface resistance) and strong proximity effect (small DF/S interface resistance). We will show that in the former case the condition is equivalent to the one of Ref. 21 , while in the latter case the new condition is found. The calculation will be performed in the zero-temperature regime by varying the interface resistances as well as the resistance, the exchange field and the Thouless energy of the DF layer.We consider a junction consisting of normal and superconducting reservoirs connected by a quasi-onedimensional diffusive ferromagnet conductor (DF) with a resistance R d and a length L much larger than the mean free path. The DF/N interface located at x = 0 has the resistance R ′ b , while the DF/S interface...

show abstract

“…For instance, it was found [4] that the transition temperature T c of the F M/SC multilayers oscillates as a function of the F M thickness. This curious behavior has been attributed to the formation of an effective π-junction [11].…”

Section: Introductionmentioning

confidence: 99%

Andreev bound states in ferromagnet-superconductor nanostructures

Krawiec

Győrffy

Annett

2003

Physica C: Superconductivity

View full text Add to dashboard Cite

We discuss the properties of a ferromagnet -superconductor heterostructure on the basis of a Hubbard model featuring exchange splitting in the ferromagnet and electron -electron attraction in the superconductor. We have solved the spinpolarized Hartree -Fock -Gorkov equations together with the Maxwell's equation (Ampere's law) fully self-consistently. We have found that a Proximity EffectFulde -Ferrell -Larkin -Ovchinnikov state is realized in such a heterostructure. It manifests itself in an oscillatory behavior of the pairing amplitude in the ferromagnet and spontaneously generated spin polarized current in the ground state. We argue that it is built up from the Andreev bound states, whose energy can be tuned by the exchange splitting and hence can coincide with the Fermi energy giving rise to a current carrying π-state. We also suggest experiments to verify these predictions.

show abstract

Transition temperatures of superconductor-ferromagnet superlattices

Cited by 352 publications

References 17 publications

Interface transparency of superconductor/ferromagnetic multilayers

Interface transparency of superconductor/ferromagnetic multilayers

Resonant peak in the density of states in normal-metal/diffusive-ferromagnet/superconductor junctions

Andreev bound states in ferromagnet-superconductor nanostructures

Contact Info

Product

Resources

About