Flux Pinning Mechanisms

Matsushita, Teruo

doi:10.1007/978-3-540-44515-9_6

Cited by 5 publications

(2 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is known that thermally activated flux creep is very prominent in HTS at high temperatures2021. According to the flux creep model19, , where ρ 0 is the normal state resistance, k is the Boltzmann constant and U 0 is the pinning potential.…”

Section: Resultsmentioning

confidence: 99%

Thickness controlled proximity effects in C-type antiferromagnet/superconductor heterostructure

Mani

Kumary

Lin

2015

Sci Rep

View full text Add to dashboard Cite

Modulation of the superconducting state possessing a C-type antiferromagnetic phase in the Nd 0.35 Sr 0.65 MnO 3 /YBa 2 Cu 3 O 7 heterostructure is investigated, with the Nd 0.35 Sr 0.65 MnO 3 thickness (t) varying from 40 to 200 nm. Both the superconducting transition temperature and the upper critical field along the c-axis decrease with increasing t; while the in-plane coherence length increases from 2.0 up to 3.6 nm. Meanwhile, the critical current density exhibits a field-independent behavior, indicating an enhanced flux pinning effect. Furthermore, low-temperature spin canting induces a breakdown and re-entrance of the superconductivity, demonstrating a dynamic completion between the superconducting pairing and the exchange field. An unexpected colossal magnetoresistance is observed below the superconducting re-entrance temperature at t = 200 nm, which is attributed to the dominant influence of the exchange field over the pairing energy.Investigating the proximity effect between different ordered phases provides unique opportunities to study fundamental physics as well as new phenomena for applications [1][2][3][4][5] . The re-discovery of colossal magnetoresistance (CMR) materials 6 and their compatibility with high-temperature superconductors (HTS) 7 to form coherent heterostructures have further intensified the research in the area of the proximity effect [8][9][10][11] . In general, superconductivity is incompatible with ferromagnetism owing to the breaking apart of the Cooper pairs by the exchange field. A recent report has demonstrated the interference effects between a quasiparticle and electron in the conductance across the YBa 2 Cu 3 O 7 (YBCO)/La 0.7 Ca 0.3 MnO 3 interface, which establishes an understanding for the long-range proximity effects between d-wave superconductivity and half-metallic ferromagnetism 12 . In addition, the strength of the exchange interaction may be modulated by modifying the form of the thin film, making this process suitable for tailoring the critical parameters of superconductors for technological applications 13,14 . It is known that Nd 0.35 Sr 0.65 MnO 3 (NSMO) exhibits C-type antiferromagnetism 15,16 below the Néel temperature (T N = 270 K), with spins aligned ferromagnetically along the c-direction but antiferromagnetically coupled within the a-b plane. However, NSMO exhibits a canted ferromagnetic (FM) phase at around 50 K via the action of the mobile electron hopping 17 . Our previous study revealed that the proximity effect of spin canting in NSMO led to a finite resistance and effective flux pinning at the superconducting state of YBCO/NSMO 10 . In general, the proximity effect of the superconducting and antiferromagnetic (AFM) orderings is much less explored because the AFM interaction does not create an internal field significant enough to affect superconductivity. The reason NSMO has considerable effect upon YBCO is that NSMO is not an isotropic antiferromagnet (G-type) but is a C-type antiferromagnet, meaning that the Mn moment aligns parallel along the c-a...

show abstract

Section: Resultsmentioning

confidence: 99%

Thickness controlled proximity effects in C-type antiferromagnet/superconductor heterostructure

Mani

Kumary

Lin

2015

Sci Rep

View full text Add to dashboard Cite

show abstract

“…Compared to other methods attempted, SiC doping is considered as the convenient and effective way to enhance the J c -B properties of superconducting MgB 2 despite of a slight reduction in T c [1]. However, while the grain boundaries are widely claimed to be the dominant pinning centers [2], the flux pinning mechanism has not yet completely clear. Yamada et al [3] explained that SiC changes the a-axis lattice constant and C substitutes for B. Matsumoto et al [4] explained that SiC-doped samples contain a significant density of various nanoscale precipitates as additional pinning centers.…”

Section: Introductionmentioning

confidence: 99%

Critical Current Density and Flux Pinning Properties in Superconducting MgB<sub>2</sub> with and without SiC Doping

Sun

Matsumoto

et al. 2013

MSF

View full text Add to dashboard Cite

It is well known that SiC doping in superconducting MgB2 improves the upper critical magnetic field (Bc2) and the critical current density (Jc) under high magnetic field. However, the relationship between SiC doping and the flux pinning mechanism has not been clarified. In this study, several MgB2 samples with and without SiC doping were prepared by the conventional in situ powder-in-tube method. The critical current densities and the force-displacement characteristics of fluxoids in samples were investigated by an ac inductive measurement (Campbell’s method). The Labusch parameter (αL) and the interaction distance (di) were estimated from the obtained force-displacement profile. It was found that SiC doping enhances the values of αL, but does not change the characteristics of the magnetic field dependence of αL apparently. Namely, αL vs. B3/2 characteristics in the pure samples and SiC doped samples are almost the same. Such a result of αL properties implies that the pinning mechanism in the SiC doped samples could be consistent with the conventional pinning theory. On the other hand, di, which is considered to be proportional to the size of pinning potential, decreases rapidly with increasing magnetic field, especially in the pure samples. For high magnetic field region, the variations of di were deduced to be caused by flux creep. The depth of pinning potential, U0, was estimated by using the values of αL and di. The values of U0 give evidence of that SiC doping can prevent the flux bundles moving to another pinning center under high magnetic field.

show abstract

Critical current enhancement in a superconducting nanolayer proximitized to a weak-ferromagnetic film

et al. 2022

View full text Add to dashboard Cite

Flux Pinning Mechanisms

Cited by 5 publications

References 27 publications

Thickness controlled proximity effects in C-type antiferromagnet/superconductor heterostructure

Thickness controlled proximity effects in C-type antiferromagnet/superconductor heterostructure

Critical Current Density and Flux Pinning Properties in Superconducting MgB<sub>2</sub> with and without SiC Doping

Critical current enhancement in a superconducting nanolayer proximitized to a weak-ferromagnetic film

Contact Info

Product

Resources

About