X-Nico

Spin density wave

The concept of a nesting vector is illustrated in the Figure for the famous case of Cr, which transitions from a paramagnetic to SDW state at a Néel temperature of 311 K. Cr is a body-centered cubic metal whose Fermi surface features many parallel boundaries between electron pockets centered at $\backslash Gamma$ and hole pockets at H. These large parallel regions can be spanned by the nesting wavevector $q$ shown in red.

see also