Paramagnetic response in a Pb-porous glass nanocomposite superconductor

Charnaya, E. V.; Lee, M.K.; Ciou, Y. S.; Tien, Cheng; Chang, Liang; Kumzerov, Yu. A.

doi:10.1016/j.physc.2013.10.004

Cited by 4 publications

(4 citation statements)

References 27 publications

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“…In addition, we observed the pronounced paramagnetic Meissner effect in O-In and O-Hg. Our previous studies revealed a similar behavior 21 for other confinement with much narrower pores. To determine T c from the dc magnetization, we choose the onset point of diamagnetism from the ZFC curves.…”

Section: Resultssupporting

confidence: 74%

The morphologic correlation between vortex transformation and upper critical field line in opal-based nanocomposites

Lee

Charnaya

Mühlbauer

et al. 2021

Sci Rep

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In this study, we investigate metallic nanocomposites to elucidate the properties of nanostructured conventional superconductors. Liquid tin, indium, and mercury are loaded into opal matrices by high pressure up to 10 kbar. The opal templates preserve the 3D dendritic morphology of confined superconducting metals to model a dendritic second phase with particular grain shape in bulk superconductors observed by a DualBeam microscope. We carry out measurements of the dc and ac magnetizations to study the superconducting phase diagrams, vortex dynamics, and impact of grain morphology in the opal composites. Besides, we apply the small-angle neutron scattering (SANS) to deny a regular vortex structure. The phase diagrams reveal an enhanced upper critical field Hc2(0) and curvature crossover in the upper critical field line. We also calculate the vortex activation barriers Ua and observe a transformation in the vortex system. According to the field dependence of Ua, the vortex structure transformation highly correlates with the curvature crossover in the upper critical field line. Our observations suggest that the similarity in the normalized phase diagrams and field dependences of Ua in the three nanocomposites is owing to their particular morphology of confinement.

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Section: Resultssupporting

confidence: 74%

The morphologic correlation between vortex transformation and upper critical field line in opal-based nanocomposites

Lee

Charnaya

Mühlbauer

et al. 2021

Sci Rep

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“…Paramagnetism in superconductors has been observed under field cooling in high temperature superconductors [25][26][27][28][29][30][31], in small or porous samples of Nb, Al, and Pb [24,[32][33][34][35], and layered systems with superconducting and magnetic materials [36][37][38]. It has been suggested that the paramagnetic Meissner effect (PME) can arise due to vortex fluctuations combined with pinning [25], phase-shifts of π originating from disorder or impurities [39][40][41][42], and intrinsic π-junctions in d-wave superconductors [43].…”

Section: On the Influence Of Stray Fieldsmentioning

confidence: 99%

Anti-Lenz supercurrents in superconducting spin valves

et al. 2017

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Here, we present a study on Si(111)/Ta(150 Å)/IrMn(150 Å)/NiFe(50 Å)/Nb(x)/NiFe(50 Å)/-Ta(50 Å) and Si(111)/Ta(150 Å)/NiFe(50 Å)/Nb(x)/NiFe(50 Å)/IrMn(150 Å)/Ta(50 Å) spin-valves with x = 100 to 500 Å. For both sample families, above a specific critical thickness of the Nblayer and below Tc, the superconducting Nb-layer contributes strongly to the magnetization. These systems show an anomalous hysteresis loop in the magnetization of the superconducting layer; the hysteresis loop is similar to what is generally expected from hard superconductors and many superconductor/ferromagnet hybrid systems, but the direction of the hysteresis loop is inverted when compared to what is generally observed (paramagnetic for up sweeping fields and diamagnetic for down sweeping fields). This means that the respective samples exhibit a magnetization, which is contrary to what should be expected from the Lenz' rule.

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“…Since then, the PME was observed in a variety of metallic superconductors [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48], and in different forms such as thin films [49][50][51][52], nanowire arrays [53], multilayer systems [54][55][56][57][58][59], and very importantly, in nanocomposites [60,61] and mesoscopic structured samples [62][63][64][65][66]. Multilayered materials may be composed of superconductor/normal metal, but also superconducting/para-or ferromagnetic ones.…”

Section: Introductionmentioning

confidence: 99%

“…The inset gives the standard measurement at low applied field. Reprinted with permission from ref [33]…”

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confidence: 99%

The Paramagnetic Meissner Effect (PME) in Metallic Superconductors

Koblischka

Půst

Chang

et al. 2023

Metals

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The experimental data in the literature concerning the Paramagnetic Meissner Effect (PME) or also called Wohlleben effect are reviewed with the emphasis on the PME exhibited by metallic, s-wave superconductors. The PME was observed in field-cool cooling (FC-C) and field-cool warming (FC-W) m(T)-measurements on Al, Nb, Pb, Ta, in compounds such as, e.g., NbSe2, In-Sn, ZrB12, and others, and also in MgB2, the metallic superconductor with the highest transition temperature. Furthermore, samples with different shapes such as crystals, polycrystals, thin films, bi- and multilayers, nanocomposites, nanowires, mesoscopic objects, and porous materials exhibited the PME. The characteristic features of the PME, found mainly in Nb disks, such as the characteristic temperatures T1 and Tp and the apparative details of the various magnetic measurement techniques applied to observe the PME, are discussed. We also show that PME can be observed with the magnetic field applied parallel and perpendicular to the sample surface, that PME can be removed by abrading the sample surface, and that PME can be introduced or enhanced by irradiation processes. The PME can be observed as well in magnetization loops (MHLs, m(H)) in a narrow temperature window Tp<Tc, which enables the construction of a phase diagram for a superconducting sample exhibiting the PME. We found that the Nb disks still exhibit the PME after more than 20 years, and we present the efforts of magnetic imaging techniques (scanning SQUID microscopy, magneto-optics, diamond nitrogen-vacancy (NV)-center magnetometry, and low-energy muon spin spectroscopy, (LE-μSR)). Various attempts to explain PME behavior are discussed in detail. In particular, magnetic measurements of mesoscopic Al disks brought out important details employing the models of a giant vortex state and flux compression. Thus, we consider these approaches and demagnetization effects as the base to understand the formation of the paramagnetic signals in most of the materials investigated. New developments and novel directions for further experimental and theoretical analysis are also outlined.

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Paramagnetic response in a Pb-porous glass nanocomposite superconductor

Cited by 4 publications

References 27 publications

The morphologic correlation between vortex transformation and upper critical field line in opal-based nanocomposites

The morphologic correlation between vortex transformation and upper critical field line in opal-based nanocomposites

Anti-Lenz supercurrents in superconducting spin valves

The Paramagnetic Meissner Effect (PME) in Metallic Superconductors

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