Thermal transport in polycrystalline YBa2Cu3O7−δ, Y2BaCuO5 and melt-processed YBa2Cu3O7−δ materials

The Investigation of Vortex Motion in the YBCO Devices Manufactured Utilizing a Gaussian-shaped Optical Spot from a Continuous-wave Laser

“…The δ ~ 0.2 degrees of optically induced deoxygenation was estimated at room temperature using the scanning electron microscope, the X-ray energy dispersive system, and also using the room-temperature resistivity and the resistivity versus temperature dependences data for the normal-state YBCO films given, as discussed ref. [23,24]. As it was predicted for the optical spot of Gaussian shape (inset of Fig.…”

“…The wavy character of the I-V characteristics is attributable to variation in the concentration of moving vortex bundles, which generates different levels of energy dissipation in the mixed-state material in the YBCO stripes. The level of energy dissipation in mixed-state material depends on the ratio between the FL and F p amplitudes [23]. The F L is almost linearly dependent on the bias current amplitude, but the F p depends on many various factors related to the shape and homogeneity of the oxygen-depleted region, the escarpment of its slopes, and the dynamics of local temperature, which is, in its turn, related to the concentration and speed of moving vortices in this region.…”

Investigation of the I – V characteristics asymmetry in semiconducting Y–Ba–Cu–O diodes

“…the electric resistance remained almost constant or even slightly increased with a decreasing temperature in the 300–100 K range [10]. An oxygen‐depletion level x in the mesa's neck had been estimated by comparing the room‐temperature electric resistance, electric resistivity dependence on temperature, and the T c value of a partly oxygen‐depleted YBCO film [6, 8, 10]. Large distributions of x values observed in some of the mesas have been related to a selective chemical etching of the YBCO film containing randomly distributed 2D and 3D defects in the crystalline structure (e.g.…”

“…In general, the electric properties of the normal‐state YBCO material strongly depend on the oxygen doping level x since it affects the Cu 2+ /Cu 3+ ratio of mixed valence cooper ions in the material's crystalline lattice [9]. The impact of oxygen deficiency on the size of a unit cell [10], orthorhombic‐to‐tetragonal structural transition [11], pyroelectricity [12], electric resistivity versus temperature dependence [6, 8], the T c value [10], and the critical current density J c versus temperature dependence [9] have been exhaustively studied for both YBCO crystals and amorphous/epitaxial thin films.…”

“…A doping-level-dependent wide range of electric conductivities can be reached in the YBa 2 Cu 3 O 7-x (YBCO) material, characterised as a triplet perovskite with a cation ordering [6][7][8]. At temperatures T > T c (T c ∼ 92 K is the onset temperature of the superconducting state in the material), a YBCO material in its optimally doped by oxygen (x ∼ 0) state is a type-II high-T c superconductor and in its normal (i.e.…”