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Luzhbin, Dmytro; Pan, Alexey V.; Komashko, V. A.; Flis, V. S.; Pan, V. M.; Dou, Shi Xue; Esquinazi, P.

doi:10.1103/physrevb.69.024506

Cited by 36 publications

(27 citation statements)

References 28 publications

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“…A decrease of d results in an increase of the superconducting T c and the SC volume fraction of the films. The upturn of the susceptibility in the SC state is probably caused by the paramagnetic Meissner effect (Wohlleben effect) [21][22][23][24] . The large value of the diamagnetic signal at low temperatures suggests that an essential volume of the films is in the SC state at low T (see inset of Fig.…”

Section: Resultsmentioning

confidence: 99%

Strain induced superconductivity in the parent compound BaFe2As2

Engelmann

Grinenko

Chekhonin³

et al. 2013

Nat Commun

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The discovery of superconductivity (SC) with a transition temperature, T c , up to 65 K in single-layer FeSe (bulk T c = 8 K) films grown on SrTiO 3 substrates has attracted special attention to Fe-based thin films. The high T c is a consequence of the combined effect of electron transfer from the oxygen-vacant substrate to the FeSe thin film and lattice tensile strain. Here we demonstrate the realization of SC in the parent compound BaFe 2 As 2 (no bulk T c ) just by tensile lattice strain without charge doping. We investigate the interplay between strain and SC in epitaxial BaFe 2 As 2 thin films on Fe-buffered MgAl 2 O 4 single crystalline substrates. The strong interfacial bonding between Fe and the FeAs sublattice increases the Fe-Fe distance due to the lattice misfit which leads to a suppression of the antiferromagnetic spin density wave and induces SC with bulk-T c ≈ 10 K. These results highlight the role of structural changes in controlling the phase diagram of Fe-based superconductors.

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Section: Resultsmentioning

confidence: 99%

Strain induced superconductivity in the parent compound BaFe2As2

Engelmann

Grinenko

Chekhonin³

et al. 2013

Nat Commun

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“…It contradicts to (i) the enhancement of B irr and T irr in increasing frequencies from as low as 20 Hz [32] to the so-called depinning frequency [33][34][35] due to the increasing immobility of vortices as the response to the increasing frequency; and to (ii) the onset of dissipations above the depinning frequency [36] explained within the mean-field model [37]. In addition, the flux diffusion and magnetization relaxation also indicate a different origin to the so-called Paramagnetic effect measured in MPMS, where temperature and field inhomogeneities experienced by samples during measurements induced highly inhomo- geneous spatial redistribution of vortices [38]. In summary, we demonstrated how the measurements nominally providing "the same" information can strongly influence its interpretation, J c , and even the behaviour of the superconductors on the example of YBCO film and MgB 2 bulk samples affected by thermal fluctuations.…”

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confidence: 99%

Critical current density: Measurements vs. reality

Pan

Golovchanskiy

Fedoseev

2013

EPL

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Different experimental techniques are employed to evaluate the critical current density ( Jc), namely transport current measurements and two different magnetisation measurements forming quasi-equilibrium and dynamic critical states. Our technique-dependent results for superconducting YBa 2Cu3O7 (YBCO) film and MgB2 bulk samples show an extremely high sensitivity of Jc and associated interpretations, such as irreversibility fields and Kramer plots, which lose meaning without a universal approach. We propose such approach for YBCO films based on their unique pinning features. This approach allows us to accurately recalculate the magnetic-field-dependent Jc obtained by any technique into the Jc behaviour, which would have been measured by any other method without performing the corresponding experiments. We also discovered low-frequency-dependent phenomena, governing flux dynamics, but contradicting the considered ones in the literature. The understanding of these phenomena, relevant to applications with moving superconductors, can clarify their dramatic impact on the electric-field criterion through flux diffusivity and corresponding measurements. © Copyright EPLA, 2013. Abstract -Different experimental techniques are employed to evaluate the critical current density (Jc), namely transport current measurements and two different magnetization measurements forming quasi-equilibrium and dynamic critical states. Our technique-dependent results for superconducting YBa2Cu3O7 (YBCO) film and MgB2 bulk samples show extremely high sensitivity of Jc and associated interpretations, such as irreversibility fields and Kramer plots, which lose meaning without an universal approach. We propose such approach for YBCO films based on their unique pinning features, which allow us to recalculate vortex behaviour affected by the measurements into the real Jc independent of measurement techniques. We also discovered low frequency-dependent phenomena, governing flux dynamics, but contradicting to the considered ones in the literature. The understanding of these phenomena, relevant to applications with moving superconductors, can clarify their dramatic impact on the electric field criterion through flux diffusivity and corresponding measurements.Superconductivity is one of the most fascinating and promising phenomena in nature. It offers benefits of no energy losses in electricity handling due to the absence of resistance below the critical temperature, as well as variety of quantum phenomena, e.g. magnetic flux quanta (vortices) whose immobilization is the key to achieving zero resistance [1] in practical superconductors.

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“…Ref. [16]); (ii) Inhomogeneities of the magnetic field in the plane perpendicular to the z-axis (across the bore of the magnet), hence any displacement from the perfect zaxis movement would be felt by the superconductor; (iii) Tilting of the superconductor relative to external magnetic field (as for the Vibrating Reed experiments [13,57]. The first two reasons are the consequences of the geometry of the PPMS superconducting magnets, whereas the third reason might arise due to various mechanical imperfections of vibration mechanism.…”

Section: Possible Origin Of Vibration-induced Phenomenamentioning

confidence: 99%

“…[1,2,3,4], but is somewhat similar to the observed shift of the irreversibility line in Refs. [8,9,16], while exhibiting unexpected, vibration driven vortex dynamics.…”

Section: Introductionmentioning

confidence: 97%

Vibration effect on magnetization and critical current density of superconductors

Golovchanskiy¹,

Pan²,

George³

et al. 2016

Supercond. Sci. Technol.

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. (2016). Vibration effect on magnetization and critical current density of superconductors. Superconductor Science and Technology, 29 075002-1-075002-12. Vibration effect on magnetization and critical current density of superconductors AbstractIn this work the effect of vibrations on critical current density ( Jc) of superconductors has been studied. The vibrations are shown to affect Jc of all types of superconductors during their measurements, employing a vibrating sample magnetometer (VSM). Increasing vibration frequency ( f ) and/or amplitude (A) leads to progressive reduction of Jc as a function of magnetic field (Ba). The effect of vibrations is substantially stronger in thin films. It leads to development of unexpected kinks on Jc (Ba) curves. Analysis of magnetization loops and relaxation of magnetization in YBCO films revealed that the vibration effect can be treated as the effective reduction of pinning potential. The asymmetry of the vibration effect in ascending and descending Ba is observed, indicating differences in free energy of the corresponding vortex structures. Thermal effects induced by vibrations with large f and A are shown to have rather insignificant influence, while the vibrational vortex dynamics exhibit a strong impact. The irreversibility field (Birr) is shown to be instrumentally defined, and its value depends on VSM settings. In addition, the practical importance of Birr for Jc modeling is demonstrated. Abstract.In this work the effect of vibrations on critical current density (Jc) of superconductors has been studied. The vibrations are shown to affect Jc of all types of superconductors during their measurements, employing Vibrating Sample Magnetometer (VSM). Increasing vibration frequency (f ) and/or amplitude (A) lead to progressive reduction of Jc as a function of magnetic field (Ba). The effect of vibrations is substantially stronger in thin films. It leads to development of unexpected kinks on Jc(Ba) curves. Analysis of magnetization loops and relaxation of magnetization in YBCO films revealed that the vibration effect can be treated as the effective reduction of pinning potential. The asymmetry of the vibration effect in ascending and descending Ba is observed, indicating differences in free energy of the corresponding vortex structures. Thermal effects induced by vibrations with large f and A is shown to have rather insignificant influence, while the vibrational vortex dynamics exhibits a strong impact. The irreversibility field (B irr ) is shown to be instrumentally defined, and its value depends on VSM settings. In addition, the practical importance of B irr for Jc modeling is demonstrated.Vibration effect on magnetization and critical current density of superconductors 2

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Origin of paramagnetic magnetization in field-cooledYBa2Cu3O7<

Cited by 36 publications

References 28 publications

Strain induced superconductivity in the parent compound BaFe2As2

Strain induced superconductivity in the parent compound BaFe2As2

Critical current density: Measurements vs. reality

Vibration effect on magnetization and critical current density of superconductors

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