Dislocation-mediated creep of highly separated vortices in a-axis-oriented HgBa2CaCu2O6+delta thin films
2001 (English)In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 64, no 2Article in journal (Refereed) Published
Using ac susceptibility, we determine the critical current density J(c) and the flux creep activation energy U of an a-axis-oriented HgBa2CaCu2O6+delta thin film. The critical current density at helium temperatures is found to be 4.6 x 10(4) A/cm(2), i.e., about two orders of magnitude smaller than for corresponding films with c-axis orientation. The temperature and ac field dependent activation energy is consistent with dislocation-mediated flux creep and well described by U(T,H-ac)=U-o(1-t(4))H-ac(-1/2) with t=T/T-c, T-c=120K, and U-o = 0.77 eV Oe(1/2) for temperatures T>45 K and in the field range studied. The activation energy is of the same order as that found in c-axis-oriented films. Below T = 45 K the activation energy is observed to decrease as thermally assisted quantum creep becomes increasingly important.
Place, publisher, year, edition, pages
2001. Vol. 64, no 2
high-tc superconductors, quantum collective creep, flux-creep, magnetic-relaxation, thermodynamic parameters, c superconductors, single-crystals, temperature, dependence, yba2cu3o7-delta
IdentifiersURN: urn:nbn:se:kth:diva-20788ISI: 000169835700103OAI: oai:DiVA.org:kth-20788DiVA: diva2:339485
QC 201005252010-08-102010-08-10Bibliographically approved