magnesium boride is one of the most promising superconductors in the world. It has many unusual characteristics and will change how we view superconductivity in the future.
It becomes superconducting at about 40 K and retains this property even after doping with carbon. It is one of the few low-temperature superconductors that does not need liquid helium to cool it, making it ideal for power transmission lines and magnetic resonance imaging (MRI) machines.
MgB2 has a large s-wave superconducting gap and a relatively small p-wave gap, which are the result of the different electron bands in the boron atoms. These differences, in turn, reflect the different electron-phonon interaction mechanisms that are modeled by BCS theory.
Its upper critical field is remarkably anisotropic, and it has been shown that the strength needed to destroy superconductivity in bulk MgB2 depends on how the crystal axes are oriented. This feature makes MgB2 a potential candidate for high-energy particle accelerators and for superconducting radio frequency (SRF) cavities.
Compared with the industrial standards Nb 3Sn and Nb-Ti, MgB2 has a higher critical current density and a significantly higher upper critical field. It also has a lower electrical resistivity, meaning that it may be more lightweight and less expensive to make than the current standards.
MgB2 has a wide range of applications, including power cables, microwave devices and commercial MRI machines. It is also used in superconducting magnets, electric motors and generators, fault current limiters and current leads. It is especially useful in superconducting radio frequency cavities because of its high upper critical field and low energy loss.