Central peak position in magnetization hysteresis loops of ferromagnet/superconductor/ferromagnet trilayered films

Kobayashi, Satoru; Oike, Hiromi; Takeda, M.; Itoh, Fumitake

doi:10.1103/physrevb.66.214520

Cited by 14 publications

(13 citation statements)

References 13 publications

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“…On the other hand, a considerable research interest has been devoted to study the physical properties of the trilayer systems both experimentally and theoretically in recent years. For example, NiFe/NiO/Co [1], Co/M/Fe 3 O 4 [2], NiFe/Cu/IrMn [3], Co/Ge/Co [4], Au/FePt/Au [5], LaBiMnO 3 /MgO/Co [6], Fe/Cr/Fe [7], NiFe/Bi/ NiFe [8], Co/Nb/Fe [9], Ni/Cu/Co [10], Co/Nb/Co [11], FeCo/Au/FeCo [12], NiFe/NB/ NiFe [13], Fe/MgO/Fe [14], Fe/Al/Fe [15], Pt/Co/Pt [16], FePt/Pt/Cr [17], YBCO/LCMO/YBCO [18], NiFe/FeMn/NiFe [19] have been studied experimentally. One can cite many more experimental works on trilayer systems.…”

Section: Introductionmentioning

confidence: 99%

Effective-field theory of the Ising model with three alternative layers on the honeycomb and square lattices

Deviren

Canko

Keskín

2008

Journal of Magnetism and Magnetic Materials

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Section: Introductionmentioning

confidence: 99%

Effective-field theory of the Ising model with three alternative layers on the honeycomb and square lattices

Deviren

Canko

Keskín

2008

Journal of Magnetism and Magnetic Materials

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“…17 is because the superconductor thickness was greater than the vortex diameter 2ξ GL < d S , where electrons in the ferromagnet are away from vortex magnetic field influence. This result was confirmed in our Nb/Co bilayer, where 2ξ GL < d S as a result of the shorter mean free path of the Nb sputtered layer that leads to a smaller ξ GL .…”

Section: A Vortex Flipping Effectmentioning

confidence: 99%

“…Evidence of these has been reported for Co/Nb/Co trilayer structures with thick Co layers measured by magnetization and critical current measurements. 17,18 In a multidomain state, the overall domain configuration is what gives the net magnetization; in particular at coercive fields, this configuration is such that the overall magnetization is zero.…”

Section: Introductionmentioning

confidence: 99%

Vortex flipping in superconductor/ferromagnet spin-valve structures

et al. 2013

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We report in-plane magnetization measurements on Ni/Nb/Ni/CoO and Co/Nb/Co/CoO spin valve structures with one of the ferromagnetic layers pinned by an antiferromagnetic layer. In samples with Ni below the superconducting transition T c , our results show strong evidence of vortex flipping driven by ferromagnet magnetization. This is a direct consequence of the proximity effect that leads to vortex supercurrent leakage into the ferromagnets. Here, the polarized electron spins are subject to the vortices' magnetic field, occasioning vortex flipping. Such a novel mechanism has been made possible by fabrication of the ferromagnet/superconductor/ferromagnet/antiferromagnet multilayered spin valves with an S layer thin enough to barely confine vortices inside as well as F layers thin enough to align and control magnetization within the plane. When Co is used, the vortex flipping effect is not observed. This is attributed to the shorter coherence length of Co. Interestingly, a reduction in the pinning field of about 400 Oe is observed instead when the Nb layer is in the superconducting state. This effect cannot be explained in terms of vortex fields. In view of these facts, any explanation must be directly related to the proximity effect and thus a remarkable phenomenon that deserves further investigation.

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“…A positive central peak on the descending field branch has also been observed from some S/F heterostructures with magnetic pinning. [43][44][45] Magnetic pinning arises from the electromagnetic interaction between the superconducting vortices and the stray field generated by the magnetic texture in the vicinity of the superconductor surface. 21 The resulting M(H) loops become highly asymmetric to the M ¼ 0 axis and only symmetric with respect to the origin, [43][44][45] in agreement with the magnetic hysteretic behavior shown in Fig.…”

Section: Discussionmentioning

confidence: 99%

Magnetic hysteresis behavior and magnetic pinning in a d ferromagnet/superconductor nanostructure

Uchino

Uenaka

Soma

et al. 2014

Journal of Applied Physics

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We investigate the interaction between superconductivity and defect-induced d0 ferromagnetism using a composite consisting of MgB2 and MgO nanocrystals. The composite exhibits a ferromagnetic hysteresis behavior in the temperature region from 40 to 300 K. Defective MgO nanocrystals (∼20 nm) embedded in the composite are considered to be responsible for the observed ferromagnetism. The zero field cool and field cool magnetization curves show that the superconducting transition occurs at Tc = 38.6 K, in agreement with Tc of pure MgB2. In the temperature region from Tc to 0.9Tc (∼35 K), the magnetization hysteresis curves show a superposition of ferromagnetic (F) and superconducting (S) signals. When the temperature of the system is decreased below 0.65Tc (∼25 K), the S signals dominate over the F signals. The resulting magnetic hysteresis loops are highly asymmetric and the descending filed branch is nearly flat, as predicted in the case of surface pinning. At temperatures below 0.5Tc (∼20 K), a sharp peak is developed near zero field in the magnetization hysteresis curves, implying an enhancement of superconducting vortex pinning. The observed pinning enhancement most likely results from magnetic pinning due to randomly distributed magnetic MgO grains, which yield the magnetic inhomogeneity and the related pinning potential in a length scale of ∼100 nm. Thus, the present ferromagnetic/superconducting composite provides an ideal model system that demonstrates the availability of d0 ferromagnetism as a source of magnetic potential for effective vortex pinning.

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Central peak position in magnetization hysteresis loops of ferromagnet/superconductor/ferromagnet trilayered films

Cited by 14 publications

References 13 publications

Effective-field theory of the Ising model with three alternative layers on the honeycomb and square lattices

Effective-field theory of the Ising model with three alternative layers on the honeycomb and square lattices

Vortex flipping in superconductor/ferromagnet spin-valve structures

Magnetic hysteresis behavior and magnetic pinning in a d ferromagnet/superconductor nanostructure

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