Superconductivity is a collective electronic state, where electrons with opposite momenta and spins (generally) pair up into bosonic objects known as Cooper pairs, and undergo a condensation. Spin-density-wave is another electronic state which possesses  magnetic order arising from periodic modulation of electronic spins. This state arises from particle-hole pairing on the appropriately shaped parts of the Fermi surface. 

We investigate how these two orders appear together in modern-day materials.