This is a general category of phenomena in condensed matter systems that cannot be understood from the stand point of non-interacting electron picture. Prominent examples of correlated phenomena include superconductivity and magnetism. 

- https://en.wikipedia.org/wiki/Fermi_gas

- Subir Sachdev http://qpt.physics.harvard.edu/publications.html

## books

https://www.amazon.com/Fundamentals-Theory-Metals-Abrikosov/dp/0486819019

[ntroduction to Modern Solid State Physics - Yuri M. Galperin](http://www.issp.ac.ru/ebooks/books/open/Introduction%20to%20Modern%20Solid%20State%20Phys.pdf)