Enhancement of superconductivity by exchange bias

Σταμόπουλος, Δ.; Manios, E.; Pissas, M.

doi:10.1103/physrevb.75.014501

Cited by 61 publications

(177 citation statements)

References 16 publications

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“…23 have shown similar measurements of M-H in NiFe-Nb system just below the T c . However, the unique behavior of two step switching and the giant coercivity observed in our system is different.…”

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confidence: 68%

Giant coercivity enhancement and dimensional crossover of superconductivity in Co₂FeSi-NbN nanoscale bilayers

et al. 2013

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Proximity coupling and magnetic switching dynamics are shown to be correlated in bilayers (B) of fully spin polarized ferromagnet (F) Co 2 FeSi and superconductor (S) NbN. The upper critical field derived from resistivity measurements shows a dimensional crossover with a reduced effective thickness of the S layer. At temperatures (T) << superconducting T c , the measured M-H loops show two step switching; one at T-independent value 7 Oe and other at strongly T-dependent value becoming very large 1 kOe at 2 K. These results reveal induced ferromagnetism in S-layer at the S/F interface with vortex pinning influenced dynamics.PACS numbers: 74.45.+c, 74.78.-w, 74.25.Op 2The research field of superconducting (S) and ferromagnetic (F) bilayers (FSB), trilayers and multilayers has gained tremendous importance 1 due to their potential for magnetoeletronics related applications 2 ranging from spin valve to Josephson junctions based devices. The two macroscopic quantum states in S and F layers influence each other via the penetration of superconducting (proximity effect) 2 and ferromagnetic (inverse proximity effect) 3-5 order through their common interface. In presence of strong enough magnetic fields, the vortices in the S-layer can couple with the magnetic domains of the F-layer leading to interesting effects of domain wall pinning of the vortices and vice-a-versa, and domain wall superconductivity [6][7][8][9][10] . Most of such studies have been carried out with ferromagnetic component consisting of 3d transition metals like Fe, Co and Ni, and their alloys. Bilayers of strongly type II superconductors with fully spin polarized ferromagnetic (FSPF) Heusler alloys, which ideally have only one spin state and can potentially show fascinating electronic properties, have not been studied yet. Recently, our group has explored the use of the Co-based Heusler compound (Co 2 MnSi) electrodes for efficient injection of pure spin currents into superconducting NbN 11 . NbN is a type II superconductor of short coherence length ( (0) 5 nm) and long penetration depth ( (0) 200 nm) while Co 2 FeSi (CFS) is a ferromagnet of the Heusler family with high magnetic ordering temperature 1150 K and saturation magnetization 6 µ B per formula unit 12 . In the present work we investigate the nature of proximity coupling and its influence on magnetic switching dynamics in the hitherto unexplored NbN/Co 2 FeSi bilayers grown on (100) MgO.Thin film bilayers of superconducting NbN and CFS were deposited by pulsed laser ablation (PLD). The 35 nm thick NbN film first deposited on MgO at 200 0 C in nitrogen environment by ablating 99.99 % Nb target and then CFS layer of 35 nm thick was grown at the same temperature from a stoichiometric CFS target. To establish the magnetic ordering in CFS film, the FSB sample was annealed at 500 0 C for 1 hour. For comparison, a pure NbN film was also grown during the same PLD run. The other growth parameters for NbN and Co 2 FeSi layers can be found in our previous reports 13,14 . The crystalline quality and interf...

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confidence: 68%

Giant coercivity enhancement and dimensional crossover of superconductivity in Co₂FeSi-NbN nanoscale bilayers

et al. 2013

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“…For instance, the modulation of the properties of a superconductor (SC) by the exchange field (superconducting spin valve effect) and/or stray fields (superconducting magnetoresistance effect) provided by an adjacent ferromagnet (FM) has been studied in great detail both experimentally [1][2][3][4][5] and theoretically 6,7 in various versions of SC/FM hybrids. Another example comes from the field of exchange bias where the exchange coupling between a FM and an adjacent antiferromagnet is effective only in the limit of thin films since the cornerstone macroscopic parameter involved in this effect, the so-called exchange bias field, is inversely proportional to the thickness of the FM layer due to the limited penetration of the coupling field inside its interior.…”

Section: Introductionmentioning

confidence: 99%

“…Here, we studied hybrids constituted of piezoelectric (PE) and ferromagnetic (FM) components in the form FM/PE/FM, ultimately aiming to provide means for the controlled modulation of the properties of the FM electrodes, originating from the strain imposed to them by the PE mediator when an electric field is applied. The PE component is in single crystal form, 0.71Pb(Mg 1/3 Nb 2/3 )O 3 -0.29PbTiO 3 (PMN-PT), while the FM outer layers are Cobalt (Co) in thin film form. Detailed magnetization measurements performed under variation of the electric field applied to PMN-PT demonstrated the efficient modulation of the properties of the Co electrodes at low temperature (coercive field modulation up to 27% and saturation magnetization absolute modulation up to 4% at T ¼ 10 K for electric field not exceeding 6 kV/cm).…”

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confidence: 99%

Modulation of the properties of thin ferromagnetic films with an externally applied electric field in ferromagnetic/piezoelectric/ferromagnetic hybrids

Σταμόπουλος

Zeibekis

Zhang

2013

Journal of Applied Physics

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Modulation of the properties of thin ferromagnetic films with an externally applied electric field in ferromagnetic/piezoelectric/ferromagnetic hybrids AbstractIn many cases, technological advances are based on artificial low-dimensional structures of heterogeneous constituents, thus called hybrids, that when come together they provide stand-alone entities that exhibit entirely different properties. Such hybrids are nowadays intensively studied since they are attractive for both basic research and oncoming practical applications. Here, we studied hybrids constituted of piezoelectric (PE) and ferromagnetic (FM) components in the form FM/PE/FM, ultimately aiming to provide means for the controlled modulation of the properties of the FM electrodes, originating from the strain imposed to them by the PE mediator when an electric field is applied. The PE component is in single crystal form, 0.71Pb(Mg1/ 3Nb 2/3)O3-0.29PbTiO3 (PMN-PT), while the FM outer layers are Cobalt (Co) in thin film form. Detailed magnetization measurements performed under variation of the electric field applied to PMN-PT demonstrated the efficient modulation of the properties of the Co electrodes at low temperature (coercive field modulation up to 27% and saturation magnetization absolute modulation up to 4% at T = 10 K for electric field not exceeding 6 kV/cm). The modulation degree faints upon increase of the temperature, evidencing that the thermal energy eventually dominates all other relevant energy scales. Candidate mechanisms are discussed for the explanation of these experimental observations. The results presented here demonstrate that commercially available materials can result in quantitatively noticeable effects. Thus, such elemental Co/PMN-PT/Co units can be used as a solid basis for the development of devices. 2013 AIP Publishing LLC. In many cases, technological advances are based on artificial low-dimensional structures of heterogeneous constituents, thus called hybrids, that when come together they provide stand-alone entities that exhibit entirely different properties. Such hybrids are nowadays intensively studied since they are attractive for both basic research and oncoming practical applications. Here, we studied hybrids constituted of piezoelectric (PE) and ferromagnetic (FM) components in the form FM/PE/FM, ultimately aiming to provide means for the controlled modulation of the properties of the FM electrodes, originating from the strain imposed to them by the PE mediator when an electric field is applied. The PE component is in single crystal form, 0.71Pb(Mg 1/3 Nb 2/3 )O 3 -0.29PbTiO 3 (PMN-PT), while the FM outer layers are Cobalt (Co) in thin film form. Detailed magnetization measurements performed under variation of the electric field applied to PMN-PT demonstrated the efficient modulation of the properties of the Co electrodes at low temperature (coercive field modulation up to 27% and saturation magnetization absolute modulation up to 4% at T ¼ 10 K for electric field not exceeding 6 kV/cm). The modulation degree fa...

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“…F/S/F heterostructures (where F and S refer to ferromagnet and superconductor, respectively) have and continue to attract much attention due to the interesting physics arising from various couplings like proximity, magnetostatic, and exchange at the S/F interface [1][2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Crossover from magnetostatic to exchange coupling in La_0.67Ca_0.33MnO₃/YBa₂Cu₃O₇/La_0.67Ca_0.33MnO₃heterostructures

Porwal

Gupta

Budhani

2016

J. Phys.: Condens. Matter

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Enhancement of superconductivity by exchange bias

Cited by 61 publications

References 16 publications

Giant coercivity enhancement and dimensional crossover of superconductivity in Co₂FeSi-NbN nanoscale bilayers

Giant coercivity enhancement and dimensional crossover of superconductivity in Co₂FeSi-NbN nanoscale bilayers

Modulation of the properties of thin ferromagnetic films with an externally applied electric field in ferromagnetic/piezoelectric/ferromagnetic hybrids

Crossover from magnetostatic to exchange coupling in La_0.67Ca_0.33MnO₃/YBa₂Cu₃O₇/La_0.67Ca_0.33MnO₃heterostructures

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Enhancement of superconductivity by exchange bias

Cited by 61 publications

References 16 publications

Giant coercivity enhancement and dimensional crossover of superconductivity in Co2FeSi-NbN nanoscale bilayers

Giant coercivity enhancement and dimensional crossover of superconductivity in Co2FeSi-NbN nanoscale bilayers

Modulation of the properties of thin ferromagnetic films with an externally applied electric field in ferromagnetic/piezoelectric/ferromagnetic hybrids

Crossover from magnetostatic to exchange coupling in La0.67Ca0.33MnO3/YBa2Cu3O7/La0.67Ca0.33MnO3heterostructures

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Giant coercivity enhancement and dimensional crossover of superconductivity in Co₂FeSi-NbN nanoscale bilayers

Giant coercivity enhancement and dimensional crossover of superconductivity in Co₂FeSi-NbN nanoscale bilayers

Crossover from magnetostatic to exchange coupling in La_0.67Ca_0.33MnO₃/YBa₂Cu₃O₇/La_0.67Ca_0.33MnO₃heterostructures