Tricritical point refers to a point where the second order phase transition curve meets the first order phase transition curve, which was first introduced by Lev Landau in 1937, wherein Landau called the tricritical point as the critical point of the continuous transition. The first example of the tricritical point was shown by Robert B. Griffiths in helium-3 helium-4 mixture. In condensed matter physics, dealing with the macroscopic physical properties of matter, a tricritical point is a point in the phase diagram of a system at which three-phase coexistence terminates. This definition is clearly parallel to the definition of an ordinary critical point as the point at which two-phase coexistence terminates.