A Review on Strain Study of Cuprate Superconductors

Abstract

Cuprate superconductors have attracted extensive attention due to their broad promising application prospects. Among the factors affecting superconductivity, the effect of strain cannot be ignored, which can significantly enhance or degrade superconductivity. In this review, we discuss and summarize the methods of applying strain to cuprate superconductors, strain measurement techniques, and the influence of strain on superconductivity. Among them, we pay special attention to the study of strain in high–temperature superconducting (HTS) films and coating. We expect this review can guide further research in the field of cuprate superconductors.

Strain effect on the high T c superconductor YBa2Cu3O7: an ab initio study comparing bulk and monolayer models

“…This would make it very difficult to compute the vibrational properties in the bulk, and the majority of the properties on the slab case due to the excessive computational time required. It is important to note that the results obtained here represent the effect of strain in samples close to optimal doping, and not in under-doped samples, where strain effects appear to be greater [25]. It would be interesting for a theoretical work to cover this problem in the future.…”

“…One possible way to achieve this is by generating strain in thin films. This strain can be induced by the mismatch with the single crystal substrate (epitaxial), or by the presence of grain boundaries, stacking faults, intergrowth, defects (residual), among others [15][16][17][18][19][20][21][22][23][24][25]. More recently, YBa 2 Cu 3 O 7 (YBCO) has been deposited on piezoelectric substrates, managing to control the range and value of the strain by applying an electric field after the sample has been grown, obtaining reversible effects on the critical temperature and a linear dependence with the in-plane strain [26,27].…”

“…Furthermore, the last one plays a role regulating the critical current and enhancing the vortex pinning process [28,32]. Therefore, in an experimental study (and also in theoretical calculations), oxygen deficiency and the presence of a compressive in-plane strain can have similar effects on the c axis (c axis enlargement) [25,33,34] and electronic properties [28,31]; knowing how the Raman modes shift under strain would allow us to discern between the presence of these two effects, as we have tried in previous works [23,35]. Furthermore, this study could be applied more directly in the analysis of YBCO samples grown on piezoelectric substrates, because strain and microstructure effects (like oxygen vacancies) can be uncoupled.…”

“…For example, another type of strain induced by mismatch between lattices originates from the artificial imposition of pinning centers between the secondary phase and the matrix. This constitutes a very important line of research in the study of HTSC, when seeking to improve its properties (like critical current and critical temperature) for applications [25,28,29]. Furthermore, strain has an important role in coated conductors and mechanical bending of the tapes in coils and cables, modifying the critical current [30].…”

Effect of Er/Y addition on the growth and superconductivity of Bi2212 films

“…The property led scientists to search for forms of high-temperature superconductors with stronger current-carrying capacity by articially designing the shape, density and distribution of pinning centers. [24][25][26][27] Related studies have shown that the nanoscale second phase has superior properties J c values as a pinning center for superconductors. In contrast, the effect of doping of Er and Y elements on Bi2212 has rarely been investigated.…”