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  2. Phase transition - Wikipedia

    en.wikipedia.org/wiki/Phase_transition

    Second-order phase transitions are continuous in the first derivative (the order parameter, which is the first derivative of the free energy with respect to the external field, is continuous across the transition) but exhibit discontinuity in a second derivative of the free energy. [6]

  3. Landau theory - Wikipedia

    en.wikipedia.org/wiki/Landau_theory

    Landau theory (also known as Ginzburg–Landau theory, despite the confusing name [1]) in physics is a theory that Lev Landau introduced in an attempt to formulate a general theory of continuous (i.e., second-order) phase transitions. [2]

  4. Ehrenfest equations - Wikipedia

    en.wikipedia.org/wiki/Ehrenfest_equations

    Ehrenfest equations (named after Paul Ehrenfest) are equations which describe changes in specific heat capacity and derivatives of specific volume in second-order phase transitions. The Clausius–Clapeyron relation does not make sense for second-order phase transitions, [ 1 ] as both specific entropy and specific volume do not change in second ...

  5. Cosmological phase transition - Wikipedia

    en.wikipedia.org/wiki/Cosmological_phase_transition

    This conclusion assumes the simplest scenario at the time of the transition, and first- or second-order transitions are possible in the presence of a quark, baryon or neutrino chemical potential, or strong magnetic fields. [12] [13] [14] The different possible phase transition types are summarised by the strong force phase diagram.

  6. Landau–de Gennes theory - Wikipedia

    en.wikipedia.org/wiki/Landau–de_Gennes_theory

    The NI transition is a first-order phase transition, albeit it is very weak. The order parameter is the Q {\displaystyle \mathbf {Q} } tensor, which is symmetric, traceless, second-order tensor and vanishes in the isotropic liquid phase.

  7. Ginzburg–Landau theory - Wikipedia

    en.wikipedia.org/wiki/Ginzburg–Landau_theory

    Based on Landau's previously established theory of second-order phase transitions, Ginzburg and Landau argued that the free energy density of a superconductor near the superconducting transition can be expressed in terms of a complex order parameter field () = | | (), where the quantity | | is a measure of the local density of superconducting electrons () analogous to a quantum mechanical wave ...

  8. Charge ordering - Wikipedia

    en.wikipedia.org/wiki/Charge_ordering

    Charge ordering (CO) is a (first- or second-order) phase transition occurring mostly in strongly correlated materials such as transition metal oxides or organic conductors. Due to the strong interaction between electrons, charges are localized on different sites leading to a disproportionation and an ordered superlattice.

  9. Quantum phase transition - Wikipedia

    en.wikipedia.org/wiki/Quantum_phase_transition

    A phase transition from a ferromagnet to a paramagnet is continuous and is of second order. (See phase transition for Ehrenfest's classification of phase transitions by the derivative of free energy which is discontinuous at the transition). These continuous transitions from an ordered to a disordered phase are described by an order parameter ...