Peak effect in a superconductingDyBa2Cu3O7−

Abstract

Peak effect in a superconducting DyBa2Cu3O7-δ film at microwave frequencies Bhangale, A.R.; Raychaudhuri, P.; Sarkar, S.; Banerjee, Tamalika; Bhagwat, S.S.; Shirodkar, V.S. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. We report the observation of a peak in the microwave ͑9.55 GHz͒ surface resistance in an epitaxial DyBa 2 Cu 3 O 7Ϫ␦ superconducting film in magnetic fields ͑parallel to the c axis͒ ranging between 0.2 to 0.9 T. Such a peak is absent in the measurements done in zero field. The temperature and field dependence of the peak suggests that this peak could be associated with the peak effect ͑PE͒ phenomenon reflecting the orderdisorder transformation in the flux-line lattice ͑FLL͒. A strong frequency dependence of the PE is observed close to the depinning frequency of the FLL.

Vortex dynamics at subcritical currents at microwave frequencies inDyBa2Cu3OBanerjee1, Bagwe2, John3 et al. 2004Phys. Rev. BSelf Cite10150View full textAdd to dashboardCite

“…Therefore, we can attribute microwave PE phenomenon to a softening of the ͑weakly pinned͒ ordered vortex lattice and a consequent transformation into a more strongly pinned amorphous solid or a pinned liquid phase. 3 Alternatively, one can also think of a plastic flow of vortex array involving the formation of channels in which the vortex array is more ordered and weakly pinned than in the surrounding areas resulting in a rise in R s . Subsequent jamming or blocking of these channels by strong pins ͑extended defects͒ hinders the flow of vortex arrays, thus reducing R s .…”

“…[1][2][3] Pinning by material disorder plays a vital role in determining the static as well as the dynamic behavior of vortices. 4 -7 Experiments such as magnetic susceptibility, surface impedance, 8,9 and vibrating reed 10,11 have a common feature that a small ac field interacts with the vortices that have penetrated the samples.…”

“…While investigating the dynamics of FLL at microwave frequencies at subcritical currents under dc magnetic fields, we have observed PE in surface resistance R s in pristine and heavy-ion irradiated DyBa 2 Cu 3 O 7Ϫ␦ ͑DBCO͒ and YBa 2 Cu 3 O 7Ϫ␦ ͑YBCO͒ thin films. 3,7 Motivated by these observations, we have carried out investigations of the defect structures responsible for the peak effect at microwave frequencies at subcritical currents and calculated depinning frequency p ͑also termed as pinning frequency by some authors earlier͒ as a function of temperature from the experimental R s data for various DBCO film thicknesses. Experimental evidence obtained on twins at the substrate-film interface and with columnar defects generated by swift Ag ion irradiation indicates that the occurrence of a peak in R s of DBCO films is associated with extended defects; whereas thicker films ͑pris-tine͒ with a high density of point defects as compared to the substrate-related twins have low R s and a large value of p and they do not show a peak in R s .…”

Effect of swift heavy ion irradiation on surface resistance of DyBa2Cu3O7-δ thin films at microwave frequencies

“…The peak is found to shift to lower temperatures with increasing field. Earlier we had proposed a model [6] where within the collective pinning scenario, since η varies smoothly with temperature, the depinning frequency, ω p (=k/η), will also show a minimum followed by a peak at the order-disorder transition. Hence, R s exhibits a dip followed by a peak close to T c .…”

“…We have shown in an earlier communication [6] the observation of PE in surface resistance (R s ) in thin films of DyBa 2 Cu 3 O 7−δ (DBCO) at subcritical currents at microwave frequencies for the first time. The dynamics of the vortices at microwave frequencies can be described by the Gittleman and Rosenblum equation of motion [7] which is defined as…”