The London depth, also known as the penetration depth, is a characteristic length scale that describes how far magnetic fields can penetrate into a superconductor. It is a measure of the superconductor's ability to expel magnetic fields.
London depth and skin depth are both measures of how far electromagnetic fields can penetrate into a material. However, they are calculated using different properties of the material. London depth is based on the superconductor's ability to expel magnetic fields, while skin depth is based on the material's electrical conductivity.
London depth is affected by the superconductor's material properties, such as its critical temperature, critical magnetic field, and coherence length. It is also influenced by the presence of impurities or defects in the material.
No, London depth can vary depending on the type of superconductor. For example, type I superconductors have a smaller London depth compared to type II superconductors, which have a larger London depth and can support higher magnetic fields.
London depth can be measured using various techniques, such as microwave measurements or magnetic field penetration experiments. These methods involve applying a magnetic field to the superconductor and measuring the changes in its electrical properties, which can then be used to calculate the London depth.