Vortex creep and critical current densities in superconducting (Ba,K)Fe2As2 single crystals

TitleVortex creep and critical current densities in superconducting (Ba,K)Fe2As2 single crystals
Publication TypeJournal Article
Year of Publication2012
AuthorsKonczykowski M, van der Beek CJ, Tanatar MA, Luo HQ, Wang ZS, Shen B, Wen HH, Prozorov R
Journal TitlePhysical Review B
Date Published07
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberWOS:000306409000005
Keywordsactivation-energies, ba-cu-o, bi2sr2cacu2o8 crystals, COLUMNAR, defects, flux-creep, glass superconductivity, high-tc superconductors, high-temperature superconductors, ii superconductors, magnetic-relaxation

The surprisingly rapid relaxation of the sustainable current density in the critical state of single-crystalline Ba1-xKxFe2As2 is investigated for magnetic fields oriented parallel to the c axis and to the ab plane, respectively. Due to the inadequacy of standard analysis procedures developed for flux creep in the high-temperature superconducting cuprates, we develop a simple, straightforward data treatment technique that reveals the creep mechanism and the creep exponent mu. At low magnetic fields, below the second magnetization peak, mu varies only slightly as a function of temperature and magnetic flux density B. From the data, we determine the temperature and field dependencies of the effective activation barrier for creep. At low temperatures, the measured current density approaches the zero-temperature critical current density (in the absence of creep) to within a factor 2, thus lending credence to earlier conclusions drawn with respect to the pinning mechanism. The comparable values of the experimental screening current density and the zero-temperature critical current density reveal the limited usefulness of the widely used "interpolation formula."

URL<Go to ISI>://WOS:000306409000005
Alternate JournalPhys. Rev. B