Nematicity is a state of matter in which particles are aligned with each other but not ordered in any particular way. In a nematic state, the particles can still move freely about, but their movements are constrained by the alignment of their neighbors. Nematicity is common in liquid crystals, and can also be found in some atomic gases and in certain solids.
The word “nematic” comes from the Greek word for thread, νήμα (nêma). This is because the first examples of nematic order were observed in thread-like molecules such as those found in DNA. However, nematic order can also be found in more complex molecules and even in atoms.
Nematicity is thought to play an important role in a number of physical phenomena, including superconductivity and quantum Hall effect. It is also believed to be responsible for the strange behavior of some materials known as “frustrated magnets”.