Superconductivity is a phenomenon where the material attains a state of zero resistance and shows perfect diamagnetism. 
The fact has been recognized first when Dutch Physicist Kamerlingh Onnes observed persistent current in Mercury at a 
temperature of 4.2 K. Later Meissner and Oschenfeld have shown that superconductors always expel magnetic field. 
The experimental facts were explained by different approaches [1][2]. First I will give an introduction about the 
phenomenological views followed by the Microscopic BCS theory [3]. Then I will discuss the experiment that shows the 
limitations of BCS theory [4].

1. F. and H. London, Proc. Roy. Soc. (London) A149, 71 (1935).
2. A. B. Pippard, Proc. Roy. Soc.(London) A216, 547 (1953)
3.J. Bardeen, L. N.Cooper, and J. R.schrieffer, Phys. Rev. 108, 1175 (1957)
4.O. Prakash, A. Kumar, A. Thamizhavel, S.Ramakrishnan, doi:10.1126/science.aaf8227 (2016)

All are cordially invited to attend