Phase separation is the creation of two distinct phases from a single homogeneous mixture.[1] The most common type of phase separation is between two immiscible liquids, such as oil and water. Colloids are formed by phase separation, though not all phase separations forms colloids - for example oil and water can form separated layers under gravity rather than remaining as microscopic droplets in suspension.
A mixture of two helium isotopes (helium-3 and helium-4) in a certain range of temperatures and concentrations separates into parts. The initial mix of the two isotopes spontaneously separates into -rich and -rich regions.[2] Phase separation also exists in ultracold gas systems.[3] It has been shown experimentally in a two-component ultracold Fermi gas case.[4][5] The phase separation can compete with other phenomena as vortex lattice formation or an exotic Fulde-Ferrell-Larkin-Ovchinnikov phase.[6]