Related papers: Angular dependent vortex pinning mechanisms in YBC…
We investigate the pinning mechanism in high-critical-current polycrystalline samples of Bi-2223 (Bi2Sr2Ca2Cu3O10) utilized in high current applications. Using differential magneto-optical (DMO) imaging technique, we track the magnetic…
The oxygen deficiency $\delta$ in YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) plays a crucial role for affecting high-temperature superconductivity. We applied (coincident) Doppler broadening spectroscopy of the electron-positron annihilation line…
Investigations into the heterogeneous pinning properties of the vortex state created by partially nano-patterning single crystals of 2H-NbSe2 reveal an atypical magnetization response which is significantly drive dependent. Analysis of the…
We have performed fluorescence x-ray absorption fine-structure (XAFS) measurements from 20-200 K on a 5000 \AA, c-axis film of YBa_2Cu_3O_{7-\delta} (YBCO) on MgO (Tc=89 K) using photons polarized perpendicular to the film. These data are…
The evolution of the vortex glass (VG) phase transition and vortex creep with decreasing film thickness is studied in ultrathin, polycrystalline niobium films, with thickness in the range 7.4 nm to 44 nm, using current-voltage…
We present a comprehensive overview of vortex pinning in single crystals of the isovalently substituted iron-based superconductor BaFe$_{2}$(As$_{1-x}$P$_{x}$)$_{2}$, a material that qualifies as an archetypical clean superconductor,…
The vortex response to various ac-drives has been studied in high quality $YBa_2Cu_4O_8$ single crystals. Well within the vortex solid phase a re-entrant resistive state has been observed that is characterized by long relaxation times.…
Measurements of the nonlinear flux-flow resistivity $\rho$ and the critical vortex velocity $\rm v^*_\phi$ at high voltage bias close to the instability regime predicted by Larkin and Ovchinnikov \cite{LO} are reported along the node and…
We present our recent results on the temperature dependence of current-voltage characteristics for polycrystalline Y_{1-x}Pr_{x}Ba_2Cu_3O_7 superconductors with x = 0.0, 0.1 and 0.3. The experimental results are found to be reasonably well…
We present surface impedance measurement of the vortex linear response in a large untwinned YBCO crystal. The depinning spectra obtained over a broad frequency range (100 Hz- 30 MHz) are those of a surface pinned vortex lattice with a free…
V(I) characteristics have been performed in a monocrystalline microbridge of $Bi[Pb]-2212$. The vortex phase diagram has been greatly investigated. Linear but non-ohmic Voltage(Current) (V(I)) curves with well defined critical current have…
We have studied a three-unit-cell-thick YBa2Cu3O7-x (YBCO) superconducting film grown on a slightly vicinal SrTiO3 substrate that was polished from the (001) plane by a small miscut angle (less than 0.5 degrees). This produced, on its…
We develop a general theory to account self-consistently for self-field effects upon the average transport critical current density Jc of a flat type-II superconducting strip in the mixed state when the bulk pinning is characterized by a…
We have measured the isothermal field dependence of magnetization of the Mo$_{100-x}$Re$_x$ (15 $\leq$ x $\leq$ 48) alloys, and have estimated the critical current and pinning force density from these measurements. We have performed…
We have measured an angle-dependent contribution to the equilibrium magnetization of a YBa_2Cu_3O_{7-d} single crystal with columnar defects created by 5.8GeV Pb ions. This contribution manifests itself as a jump in the equilibrium torque…
A study has been perfomed on the superconducting critical current density J_{c} flowing across low angle grain boundaries in epitaxial thin films of YBa{2}Cu{3}O{7-d} (YBCO). The materials studied were dual grain boundary rings deposited on…
The most effective way to enhance the dissipation-free supercurrent in presence of magnetic field for type II superconductors is the introduction of defects that acts as artificial pinning centres (APCs) for the vortices. For instance, the…
We report a detailed study performed on La2Zr2O7 (LZO) pyrochlore material grown by Metal-Organic Decomposition (MOD) method as buffer layers for YBa2Cu3O7-x (YBCO) coated conductors. High quality epitaxial LZO thin films have been obtained…
The d-wave symmetry of the order parameter with zero energy gap in nodal directions stands in the way of using high-temperature superconductors for quantum applications. We investigate the symmetry of the order parameter in ultra-thin…
The vortex contribution to the dc field (H) dependent microwave surface impedance Z_s = R_s+iX_s of YBa_2Cu_3O_{7-x} thin films was measured using suspended patterned resonators. Z_s(H) is shown to be a direct measure of the flux density…