Mechanism of pair-density-wave from electron repulsion 

While uniform superconductivity has been observed in many materials, that with finite center-of-mass momentum pairing, also known as pair-density-wave, stays rare in nature. In this talk I will introduce both weak and intermediate coupling theories to explain the underlying mechanism for PDWs from electron repulsion. The weak coupling theory generally involves Fermi surface nesting in the particle-particle channel, while the intermediate coupling theory requires local suppression and is a threshold phenomenon. Typical examples such as moire bilayer systems and Kagome metals will be discussed.