Suppose a superconductor which is in a normal state (i.e. $T>Tc$) is subjected to a magnetic field. As soon as magnetic field switched from 0 to some value, eddy currents will develop on the surface and they will die away because of finite resistance. Now if I decrease the temperature below critical temperature, normal material will become superconductor and it will expel the magnetic field immediately, cf. the Meissner effect. I want to know the reason what causes the superconductor to push away magnetic fields.
I want to know the reason what causes the superconductor to push away magnetic fields.
So, the magnetic field is pushed out of a superconductor by the currents flowing near its surface. Not sure if there exists a consensus on how exactly these currents are generated, though.