Long-range proximity effect in La<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>2</mml:mn><mml:mo>/</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>Ca<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow /><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>MnO<mml:math xmlns:mml="http://www.w3.org/1998/M

Kalcheim, Yoav; Kirzhner, T.; Koren, G.; Millo, Oded

doi:10.1103/physrevb.83.064510

Cited by 89 publications

(74 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[65][66][67][68][69] and may trigger such a transformation. The suggestion of a spintriplet nature of the observed long-range proximity effect in our insulating LMO is in accord with similar reports for half-metallic manganites [24][25][26][27].…”

Section: Discussionsupporting

confidence: 93%

“…In ferromagnetic metals the range depends on the superconducting pairing symmetry [17,18]: the conventional spin-singlet pairing is rapidly suppressed by the magnetic exchange field at the scale of ∼ 1 nm [16], but the unconventional spin-triplet pairing is immune to the magnetic exchange field and the range is similar as in non-magnetic metals. Therefore long-range superconducting proximity effects, observed in ferromagnetic metals [20][21][22] and half-metals [23][24][25][26][27] are taken as evidence for a spin-triplet superconducting state induced via spinactive S/F interfaces [17,18].S/FI/S tunnel junctions are characterized by a nontrivial phase dynamics [17,28,29] that is useful for phasecoherent quantum spintronic devices [15,28]. Atomically thin FI layers enable sizeable and almost fully spinpolarized tunnel currents that are beneficial for spintronic applications [8,13].…”

mentioning

confidence: 99%

See 1 more Smart Citation

High bias anomaly in YBa2Cu3O7−x/LaMnO
Golod
¹
,
Rydh
²
,
Krasnov
³

et al. 2013
Phys. Rev. B
28
4
29
0
View full text Add to dashboard Cite

High bias anomaly in YBa 2 Cu 3 O 7 /LaMnO 3+δ /YBa 2 Cu 3 O 7 Superconductor/Ferromagnetic Insulator/Superconductor junctions: Evidence for a long-range superconducting proximity effect through the conduction band of a ferromagnetic insulator. We study the perpendicular transport characteristics of small superconductor/ ferromagnetic insulator/ superconductor (YBa2Cu3O7−x/ LaMnO 3+δ / YBa2Cu3O7−x) tunnel junctions. At a large bias voltage V ∼ 1 V we observe a step-like onset of excess current that occurs below the superconducting transition temperature T < Tc and is easily suppressed by a magnetic field. The phenomenon is attributed to a novel type of the superconducting proximity effect of non-equilibrium electrons injected into the conduction band of the ferromagnetic insulator via a Fowler-Nordheim tunneling process. The occurrence of a strongly non-equilibrium population is confirmed by the detection of photon emission at large bias voltage. Since the conduction band in our ferromagnetic insulator is strongly spin polarized, the long-range (20 nm) of the observed proximity effect provides evidence for an unconventional spin-triplet superconducting state. I. INTRODUCTIONThe manganite perovskite La 2−x (Ca,Sr) x MnO 3 exhibits a rich phase diagram of unusual electronic and magnetic properties. Most prominent is the so-called colossal magneto-resistance (CMR) effect which occurs at 0.15 < x < 0.5 in the context of a transition from a paramagnetic and insulating or poorly conducting state to a ferromagnetic and half metallic state [1,2]. At somewhat lower doping at 0.1 < x < 0.15, the corresponding transition leads into a ferromagnetic insulating (FI) state which is a consequence of charge localization below the spin-polaron mobility edge and orbital ordering at low T [3][4][5][6]. This FI state can also be achieved in off stoichiometric LaMnO 3+δ in which the hole doping is due to La or Mn vacancies. While half-metallic manganites are considered as promising spin-polarizers [7], the FI manganite can be an ideal spin-filter material for use in tunnel barriers with low leakage currents. Efficient spin-filters are on demand for spintronic applications [8]. Spin polarization depends on many parameters including the density of states (DOS) of electronic bands [7,[9][10][11][12], orbital hybridization and various material issues at interfaces and on the bias voltage [13]. Metallic ferromagnets provide only modest spin polarization because both majority (↑) and minority (↓) spin bands are crossing the Fermi level E F [14]. This problem is obviated in insulating and halfmetallic ferromagnets with separated majority and minority bands at E F , which, therefore, can facilitate an almost complete spin-polarization [8,[13][14][15].The antagonism between superconductivity (S) and ferromagnetism (F) leads to a variety of novel effects in hybrid S/F heterostructures [16,17], such as the stabilization of unconventional spin-triplet superconductivity [17,18], or the realization of π-Josephson junctions [19], that are interest...

show abstract

Section: Discussionsupporting

confidence: 93%

mentioning

confidence: 99%

High bias anomaly in YBa2Cu3O7−x/LaMnO
Golod
¹
,
Rydh
²
,
Krasnov
³

et al. 2013
Phys. Rev. B
28
4
29
0
View full text Add to dashboard Cite

show abstract

“…Although this scenario is more probable in high-temperature superconducting (HTS) systems than in the Nb-based devices discussed here because of the availability of quasiparticle states at all energies (HTS), our results raise the intriguing possibility of the involvement of triplet pairing in this behaviour. There is increasing evidence that spin disorder at manganite-HTS interfaces creates an intrinsic spin-mixer layer [39][40][41] , and the 100% spin polarization of the manganites suggests that the dependence of the proximity effect on spin-valve configuration should be significantly higher than in systems involving half-metallic ferromagnets.…”

Section: Discussionmentioning

confidence: 99%

Evidence for spin selectivity of triplet pairs in superconducting spin valves

et al. 2014

View full text Add to dashboard Cite

Spin selectivity in a ferromagnet results from a difference in the density of up-and down-spin electrons at the Fermi energy as a consequence of which the scattering rates depend on the spin orientation of the electrons. This property is utilized in spintronics to control the flow of electrons by ferromagnets in a ferromagnet (F1)/normal metal (N)/ferromagnet (F2) spin valve, where F1 acts as the polarizer and F2 the analyser. The feasibility of superconducting spintronics depends on the spin sensitivity of ferromagnets to the spin of the equal spintriplet Cooper pairs, which arise in superconductor (S)-ferromagnet (F) heterostructures with magnetic inhomogeneity at the S-F interface. Here we report a critical temperature dependence on magnetic configuration in current-in-plane F-S-F spin valves with a holmium spin mixer at the S-F interface providing evidence of a spin selectivity of the ferromagnets to the spin of the triplet Cooper pairs.

show abstract

“…Equal-spin triplets are immune to the exchange field, and can propagate into ferromagnets over the same long distance as singlets into normal metals [2]. During recent years, various experiments have found long-range proximity effects and Josephson coupling in specific S/F systems [3][4][5][6][7][8][9], which have been interpreted in terms of singlet-to-triplet conversion. Besides its fundamental interest, equal-spin triplet superconductivity may yield novel technological applications within the field of spintronics [10].…”

mentioning

confidence: 99%

Magnetic field influence on the proximity effect atYBa2Cu3O7/L
Visani
¹
,
Cuellar
²
,
Pérez-Muñoz
³

et al. 2015
Phys. Rev. B
12
0
4
0
View full text Add to dashboard Cite

We experimentally study the superconducting proximity effect in high-temperature superconductor/halfmetallic ferromagnet YBa 2 Cu 3 O 7 /La 2/3 Ca 1/3 MnO 3 junctions, using conductance measurements. In particular, we investigate the magnetic-field dependence of the spectroscopic signatures that evidence the long-range penetration of superconducting correlations into the half-metal. Those signatures are insensitive to the applied field when this is below the ferromagnet's saturation fields, which demonstrates that they are uncorrelated with its macroscopic magnetization. However, the application of more intense fields progressively washes away the fingerprint of long-range proximity effects. This is consistent with the fact that the well-known magnetic inhomogeneities at the c-axis YBa 2 Cu 3 O 7 /La 2/3 Ca 1/3 MnO 3 interface play a role in the proximity behavior. Ferromagnetic order and singlet superconductivity are incompatible, because the magnetic exchange field breaks apart the conventional opposite-spin Cooper pairs. For this reason, the superconducting proximity effect is generally short ranged in superconductor/ferromagnet (S/F) structures [1]. However, a long-range propagation of superconducting correlations into an F is expected if a conversion from "opposite-spin singlet" to "equal-spin triplet" pairing occurs at the S/F interface [2]. Equal-spin triplets are immune to the exchange field, and can propagate into ferromagnets over the same long distance as singlets into normal metals [2]. During recent years, various experiments have found long-range proximity effects and Josephson coupling in specific S/F systems [3-9], which have been interpreted in terms of singlet-to-triplet conversion. Besides its fundamental interest, equal-spin triplet superconductivity may yield novel technological applications within the field of spintronics [10]. In this sense, half-metal ferromagnets are especially interesting, because the triplet superconducting condensate must be fully spin polarized in these materials [11].Among the half-metal-based S/F systems in which longrange proximity effects have been observed, all-oxide heterostructures that combine manganites (La x Ca 1−x MnO 3 or La x Sr 1−x MnO 3 ) and cuprate superconductors have received continued attention [8,9,[12][13][14][15][16][17][18][19]. From the early hints based on the critical temperature (T C ) measurements in S/F superlattices [14,20], to the more recent spectroscopic [8,9,19] and Josephson current measurements in S/F junctions [21], various experiments have provided evidence for longrange superconducting proximity effects in half-metallic manganites. However, the physical origin of the singletto-triplet conversion-which could be different for each cuprate/manganite combination-has not been identified. As theoretically shown for generic S/F systems, the singlet-totriplet conversion can be produced by interfacial magnetic * Present address: Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA.† javier.villegas@thalesgro...

show abstract

Long-range proximity effect in La2/3Ca1/3MnO
Yoav Kalcheim
¹
,
T. Kirzhner
²
,
G. Koren
³

et al.

Cited by 89 publications

References 39 publications

High bias anomaly in YBa2Cu3O7−x/LaMnO
Golod
¹
,
Rydh
²
,
Krasnov
³

et al. 2013
Phys. Rev. B
28
4
29
0
View full text Add to dashboard Cite

High bias anomaly in YBa2Cu3O7−x/LaMnO
Golod
¹
,
Rydh
²
,
Krasnov
³

et al. 2013
Phys. Rev. B
28
4
29
0
View full text Add to dashboard Cite

Evidence for spin selectivity of triplet pairs in superconducting spin valves

Magnetic field influence on the proximity effect atYBa2Cu3O7/L
Visani
¹
,
Cuellar
²
,
Pérez-Muñoz
³

et al. 2015
Phys. Rev. B
12
0
4
0
View full text Add to dashboard Cite

Contact Info

Product

Resources

About

Long-range proximity effect in La2/3Ca1/3MnOYoav Kalcheim1, T. Kirzhner2, G. Koren3 et al.

Cited by 89 publications

References 39 publications

High bias anomaly in YBa2Cu3O7−x/LaMnOGolod1, Rydh2, Krasnov3 et al. 2013Phys. Rev. B284290View full textAdd to dashboardCite

High bias anomaly in YBa2Cu3O7−x/LaMnOGolod1, Rydh2, Krasnov3 et al. 2013Phys. Rev. B284290View full textAdd to dashboardCite

Evidence for spin selectivity of triplet pairs in superconducting spin valves

Magnetic field influence on the proximity effect atYBa2Cu3O7/LVisani1, Cuellar2, Pérez-Muñoz3 et al. 2015Phys. Rev. B12040View full textAdd to dashboardCite

Contact Info

Product

Resources

About

Long-range proximity effect in La2/3Ca1/3MnO
Yoav Kalcheim
¹
,
T. Kirzhner
²
,
G. Koren
³

et al.

High bias anomaly in YBa2Cu3O7−x/LaMnO
Golod
¹
,
Rydh
²
,
Krasnov
³

et al. 2013
Phys. Rev. B
28
4
29
0
View full text Add to dashboard Cite

High bias anomaly in YBa2Cu3O7−x/LaMnO
Golod
¹
,
Rydh
²
,
Krasnov
³

et al. 2013
Phys. Rev. B
28
4
29
0
View full text Add to dashboard Cite

Magnetic field influence on the proximity effect atYBa2Cu3O7/L
Visani
¹
,
Cuellar
²
,
Pérez-Muñoz
³

et al. 2015
Phys. Rev. B
12
0
4
0
View full text Add to dashboard Cite