SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Lombardi Floriana 1967) srt2:(2005-2009)"

Sökning: WFRF:(Lombardi Floriana 1967) > (2005-2009)

  • Resultat 1-10 av 26
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Bauch, Thilo, 1972, et al. (författare)
  • Dynamics of d-wave YBa2Cu3O7-x
  • 2007
  • Ingår i: Superconductor Science and Technology. - 0953-2048 .- 1361-6668. ; 20:2, s. S98-S104
  • Konferensbidrag (refereegranskat)abstract
    • The predominant d-wave pairing symmetry in high temperature superconductors leads to an unconventional current phase relation in Josephson junctions. This circumstance may induce new effects in the dynamics of dc SQUIDs. In this contribution we report on the measurements of the dependence of the SQUID Josephson current on the external magnetic field taken at very low temperatures, down to 20 mK. Different grain boundaries have been fabricated by using the biepitaxial and the bicrystal technique. Some of the effects which are induced by a nonsinusoidal current phase relation can be clearly identified in the dynamics of the SQUIDs. The experimental data are also compared with theoretical simulations taking into account the inductance of the loop. The data show that, in specific conditions, a non-negligible inductance of the loop can induce effects similar to an unconventional current phase relation, with a pronounced second harmonic sin(2) term. This fact has to be taken into account when designing d-wave SQUIDs for quantum circuitry.
  •  
2.
  • Bauch, Thilo, 1972, et al. (författare)
  • High critical temperature superconductor Josephson junctions for quantum circuit applications
  • 2009
  • Ingår i: Physica Scripta. ; T137, s. 014006-
  • Konferensbidrag (refereegranskat)abstract
    • Recent findings of macroscopic quantum properties in high critical temperature superconductor (HTS) Josephson junctions (JJs) point toward the need to revise the role of zero energy quasi-particles in this novel superconductor. We will discuss the possibility of designing superconducting artificial atoms in a transmon configuration to study the low energy excitation spectra of HTS. We have engineered high quality grain boundary JJs on low dielectric constant substrates. By fabricating submicron junctions, we extract values of capacitance and Josephson critical current densities that satisfy the main transmon design requirements. Moreover, the measured critical current noise power extrapolated at 1 Hz gives a dephasing time of 25 ns, which indicates that the observation of macroscopic quantum coherent effects in HTS JJ is a feasible task.
  •  
3.
  •  
4.
  •  
5.
  • Bauch, Thilo, 1972, et al. (författare)
  • YBCOSQUIDs with unconventional current phase relation
  • 2007
  • Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 463-465:1 October 2007, s. 979-984
  • Tidskriftsartikel (refereegranskat)abstract
    • We have studied the dynamics of YBa2Cu3O7-delta,5 (YBCO) dc sperconducting quantum interference devices (SQUIDs) characterized by an unconventional Josephson current phase relation (CPR). We have focused on SQUID configurations with Josephson junctions where the lobe of the order parameter in one electrode is facing a node in the other electrode. This order parameter arrangement should enhance the appearance of a sin(2(p) term in the CPR. The response of the critical current of the dc SQUID, under the effect of an external magnetic field, has been measured in temperature, down to 20 mK. Our experimental data have been compared with numerical simulations of the SQUIDs dynamics by considering a CPR of a single junction of the form I(phi) = I-I sin(phi) - I-II sin(2 phi) where I-I, and I-II are, respectively, the first and second harmonic component. In our devices the values of the sin(2 phi) term are such that the fundamental state of the SQUID is naturally double degenerate. This is of great relevance for applications of d-wave SQUIDs in quantum information processing. (C) 2007 Elsevier B.V. All rights reserved.
  •  
6.
  • Born, D., et al. (författare)
  • CaBaCuO ultrathin films and junctions
  • 2007
  • Ingår i: IEEE Transactions on Applied Superconductivity. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2515 .- 1051-8223. ; 17:2/3, s. 3581-3584
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigated transport properties of ultrathin CaBaCuO (CBCO) bridges, focusing on vortex dynamics, and Josephson bicrystal junctions. The CBCO films used are composed of a stacking sequence of two structural subunits having different functions, namely a Ba-based charge reservoir (CR) block and a Ca-based infinite layer (IL) superconducting block. SQUID microscopy investigations of these films provide Pearl lengths A more than the bridge widths. Measuring current-voltage characteristics we found evidence that at high temperatures the vortices are thermally activated at the edge of the bridge and pushed in, causing dissipation and a power-law dependence of the voltage from the current. At lower temperatures, the experimental curves change their shape. We compared these data with the predicted behavior for vortex quantum tunneling and we found very good agreement. Moreover, we have realized Josephson junctions composed of only a few superconducting CuO2 planes. The CBCO films used in these experiments are only 8 nm thick and have six superconducting CUO2 planes. The simple structure of the GB allows a reliable estimation of the coupling along the ab planes of the CuO2. We calculate for 24 degrees symmetric and asymmetric cases a critical current density per plane of about (1-3) kA/cm(2).
  •  
7.
  •  
8.
  •  
9.
  • Gustafsson, David, 1982, et al. (författare)
  • Low capacitance HTS junctions for single electron transistors
  • 2009
  • Ingår i: Physica C: Superconductivity and its Applications. - : Elsevier BV. - 0921-4534. ; 470:SUPPL.1, s. S188-S190
  • Konferensbidrag (refereegranskat)abstract
    • We have fabricated and characterized YBa2Cu3O7-δ grain boundary junctions to determine their feasibility as tunnel barriers in single electron transistors. Superconducting quantum interference devices with injection lines have been used to measure the junctions capacitance. We have extracted capacitance values which allow us to achieve a Coulomb blockade regime for sufficiently small junction dimensions.
  •  
10.
  • Johansson, Jesper, 1979, et al. (författare)
  • Properties of inductance and magnetic penetration depth in (103)-oriented YBa2Cu3O7-delta thin films
  • 2009
  • Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 79:21, s. 214513-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a study of the anisotropy of the inductance in (103) YBa2Cu3O7-delta (YBCO) films. YBCO superconducting quantum interference devices (SQUIDs) were fabricated by the biepitaxial technique. SQUIDs with (001)- and (103)-oriented YBCO electrodes characterized by different grain-boundary angles were realized on the same chip. Two extrainjection lines were attached to the (103) YBCO electrode. These devices, when operated in current injection mode, allow us to measure the inductance of the (103) YBCO electrode. We have found that the inductance L of the (103) YBCO can differ by a factor of 20 in the two extreme cases: L determined by current transport parallel to the ab planes and L dominated by the transport in the c-axis direction. The full in-plane angular dependence of the inductance has been obtained by considering geometrically identical SQUIDs oriented with different angles with respect to the [100] direction of the (103) film. From these measurements, we have determined the London penetration depths in the ab direction lambda(ab) and the c direction lambda(c) and their temperature dependence.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 26

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy