On reversible variation of parameters of traditional and high-temperature heterophase superconductors under mechanical loading

The emergence of superelasticity in the superconducting state is considered as a reason behind the reversible variation of the parameters of superconductors under the action of an external elastic field σe. Since the superconducting parameters of the martensitic phase differ from those of the initial phase, a change in the volume concentration of the martensitic phase alters the superconducting parameters of the sample, viz., the critical current Ic and the superconducting transition temperature Tc under loading. This circumstance can be used to explain the degradation of Ic and Tc for traditional superconductors under loading and their complete (in the case of NbTi) or partial (in the case of Nb3Sn) restoration upon unloading. In high-temperature superconductors (like YBa3Cu3O7−x or La1−x Srx CuO4), the low-temperature martensitic (rhombic) phase is responsible for superconductivity, which distinguishes them from traditional superconductors and must lead to a different manifestation of the dependence of superconductivity on σe (perhaps, to an increase in Tc and Ic). Under certain conditions, the concentration of the martensite phase may change, and hence the shape and the superconducting parameters of the sample can also undergo reversible changes under the action of an external magnetic field H. In the framework of the developed approach, the reversible variation of the superconducting parameters will be observed only to certain threshold values of σe or H. The effect of “training” in traditional and high-Tc superconductors is analyzed.

Перевод пока недоступен