Superconductivity is a phenomenon where metals and other materials exhibit zero electrical resistance and perfect diamagnetism. This behavior is first observed almost a century ago in a tin and mercury alloy, and it is still a mystery to this day. Scientists have been trying to understand and exploit this unique property of superconductors as it has revolutionized many technological processes.
One of the main areas of superconductivity research is the effect of mechanical stress on these materials. Mechanical stress on superconductors could alter their superconducting properties and lead to new technologies with enhanced performance characteristics. By applying various mechanical forces， scientists can modify the atomic and electronic structure of superconductors and thus affect their superconducting state. This can be used to produce stronger magnetic flux densities, reduce material costs, and increase the critical current density or the amount of current that flows through a superconductor.
The mechanical stress effects on superconductors can be studied through various techniques such as electron microscopy, x-ray diffraction, and scanning tunneling microscopy,etc. These techniques are used to measure the strain response on the atomic and electronic structure of superconductors. Depending on the type of mechanical force applied, the strain response can be divided into reversible or irreversible strain response. Reversible strain response refers to the reversible displacement of atoms or electrons due to an applied external force and can result in a change in superconductivity. Irreversible strain response, on the other hand, occurs when the applied force causes a permanent defect in the superconductor’s structure.
At the atomic level, superconductors are lattices of atoms held together by covalent bonds. Mechanical forces can disrupt these bonds, which in turn affects the superconducting state of the material. For example, compressive forces can cause the lattice to contract, thus increasing the distance between neighboring atoms and decreasing the critical temperature of the superconductor. On the other hand, tensile forces can cause the lattice to expand, thereby decreasing the distance between neighboring ions and raising the critical temperature of the material.
In addition to altering the critical temperature, mechanical stress can also affect the pinning force of a superconductor. Pinning force is the force that imparts some of its magnetism onto the superconductor. This force also affects the critical current density, which is the amount of current that a superconductor can support before it becomes resistive. A higher critical current density is desirable, as it can increase the material’s efficiency. Therefore, mechanical stress has the potential to improve a superconductor’s performance.
The effects of mechanical stress on superconductors have been extensively studied and are still being studied for the purpose of improving technological processes using superconductors. By understanding and manipulating the mechanical response of these materials, engineers and scientists can develop new materials and devices with enhanced performance characteristics. Such enhanced performance can lead to a revolution in modern technology, where superconductors can be used in various applications from data storage to power generation.
