Based on their behavior in external magnetic fields, superconductors are divided into Type I and Type II. Imagine them as two types of goalkeepers with different styles. Type I superconductors, mostly pure metals like mercury and lead, are “all-or-nothing” defenders. Below a certain critical magnetic field, they completely expel all magnetic flux; above this field, superconductivity is destroyed and they revert to the normal state. Their binary response limits their use in high-field applications. Type II superconductors, typically alloys and HTS, are more adaptable. Between two critical fields, they allow magnetic flux to penetrate partially in the form of quantized “vortices” or “flux tubes,” while retaining superconductivity in the surrounding regions. This mixed state enables them to withstand much higher magnetic fields, making them essential for high-field magnets used in MRI machines, fusion reactors (tokamaks), and envisioned for future electric aircraft.
