Irreversibility limits of the Abrikosov and Josephson flux dynamics in homogeneous and granular high-TCsuperconductors

Abstract

The magnetic irreversibility of a high-quality YBa 2 Cu 3 O 7Ϫ␦ single crystal and of the granular superconductors YBa 1.5 Sr 0.5 Cu 3 O 7Ϫ␦ and YBa 1.75 Sr 0.25 Cu 3 O 7Ϫ␦ single crystals and the polycrystalline YBa 1.75 Sr 0.25 Cu 3 O 7Ϫ␦ sample in two different oxygen states was determined in great detail, as a function of applied field up to 5 T from zero-field-cooled and field-cooled dc magnetization. While the T irr data of the pure single crystal are well described by the power law, predicted by the flux-creep models, in the whole field range, those of the granular superconductors adhere to this power law only in the high-field region. In a low-field region two quite different regimes take place: In the lowest fields the data obey a de Almeida-Thouless-like power law and above a sharp crossover field they follow a Gabay-Toulouse-like power law. These low-field features are acknowledged as the signature of a frustrated system.

H–T phase diagram and the nature of vortex-glass phase in a quasi-two-dimensional superconductor: Sn-metal layer sandwiched between graphene sheets

“…The exponent α(gl ′ ) is close to that (= 0.50) predicted from the Gabay-Thoules (GT) theory [7]. Such an occurrence of the AT-GT crossover has been reported in granular high T c superconductors [20,21]. No GT-power law form has been observed in a single crystal of YBa 2 Cu 3 O 7 without granularity [20].…”

Flux-Line-Lattice Melting and Upper Critical Field of Bi1.65Pb0.35Sr2Ca2Cu3O10+δ Ceramic Samples

“…However, we first mention that the height of the peaks in our curves remains essentially unaltered when the applied magnetic field is increased. Such a behavior differs from those reported in other polycrystalline samples where the height of the second peak in dρ/dT curves decreases abruptly at relatively low (≤1 T) applied magnetic fields [31]. Under this circumstance, we assume that the peak in dρ/dT curves at T = T m is related to the flux-line-lattice melting or the irreversibility line at the intragranular level [3,4].…”

Anisotropic irreversibility of the Abrikosov and Josephson flux dynamics inYBa2−xSrxVieira1, Schaf2 2002Phys. Rev. BSelf Cite232120View full textAdd to dashboardCite

“…In the present work we extend our previous magnetic irreversibility ͓T irr (H)͔ study for fields along the c axis 33 to the case of fields applied along the ab planes (Hʈab). Besides large planar anisotropies and the same AT and GT power-law behaviors in low fields as for Hʈc, we identify Bose-glass and vortex-glass features in high fields.…”

“…12,30 Recently we studied the T irr (H) of Sr-doped and heavily twinned YBa 2Ϫx Sr x Cu 3 O 7Ϫ␦ single crystals (xϭ0.25 and 0.5͒ as well as of a polycrystalline sample for fields applied along the c axis (Hʈc). [30][31][32][33] The T irr (H) data of all these superconductors revealed a fc power law behavior ͓Eq. ͑1͔͒ in a major high-field region.…”