antiferromagnetism - definition - condensed matter, electromagnetism and statistical physics

Definition: Phenomenon in some magnetically ordered materials in which there is an anti-parallel alignment of spins in two interpenetrating structures so that there is no overall bulk spontaneous magnetisation. In ferromagnetic materials, it is energetically favorable for the spins atomic to align, leading to spontaneous magnetisation. However, in antiferromagnetic materials, the conditions are such that it is energetically favorable for the spins to oppose, leading to no overall magnetisation.