Impact of pseudo-gap states on the pinning energy and irreversibility field of high temperature superconductors

Abstract

The existence of pseudo-gap states at energies larger than the coherence energy scale is shown to be at the origin of the difficulties encountered in achieving strong vortex pinning in the high Tc cuprates. Reduction or elimination of the pseudo-gap states by overdoping is effective in increasing the condensation energy and the irreversibility field. In YBa2Cu3O7, a full BCS state, with a single energy scale, can be restored, leading to the highest known irreversibility field and pinning strength. In the bismuthates, the detrimental effect of the pseudo-gap states can only be mitigated to some extent by overdoping.

Direct observation of apical oxygen vacancies in the high-temperature superconductor YBa2Cu3O7−xHartman1, Mundet2, Idrobo3 et al. 2019Phys. Rev. Materials193180View full textAdd to dashboardCite

“…For instance, a recent investigation [22] of the magnetic excitations in cuprates with zero, one, or two apical oxygen per CuO 2 plane concluded that the structure without apical oxygen had the most long-range electron hopping. Likewise, any strain or distortion of the CuO 2 planes is likely to alter the pair condensation energy and its J C [3]. Hence, we consider the implications of apical V O .…”

“…Subtle changes in structure and stoichiometry stemming from defects influence many functional properties of ceramics. A paradigmatic example is the high-temperature superconductor YBa 2 Cu 3 O 7−x (YBCO), where its critical temperature (T c ) and critical current density (J c ) are governed by oxygen vacancies (V O ) [1][2][3]. The structure of YBCO, shown in Fig.…”

“…Optimal doping, at x = 0.07, gives a maximum T c of 92 K, while x > 0.55, destroys the superconducting state [1], thus controlling the oxygen stoichiometry allows a way to tune T c . J C is also modulated by the oxygen content, since the magnetic vortex pinning is sensitive to both the carrier concentration and the distortions around V O [2,3,5].…”

“…1(a). There are three other oxygen sites in YBCO, one apical site in the BaO layer, O(4), and two inequivalent sites in the CuO 2 planes, O (2) and O (3). The attention to the chain vacancies over others can be attributed to two factors.…”

Untangling surface oxygen exchange effects in YBa2Cu3O6+x thin films by electrical conductivity relaxation

“…However, oxygenation at low temperatures would be interesting because one can further modify the oxygen content of the YBCO films. [73][74][75][76] To overcome the low temperature limitation in the oxygenation of functional oxides, it has been shown that silver can be used as a catalyst to enhance the rate of oxygen incorporation. The use of silver as a catalyst for selective oxidation processes is well-known in different fields, especially in the hydrocarbon industry.…”