XY model

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The XY model, also known as the O(2) model because of its symmetry group, is a Heisenberg ferromagnetic with an easy-plane anisotropy. The Hamiltonian is given by

H = -J{\sum}_{\langle i,j\rangle}\mathbf{S}_i \cdot \mathbf{S}_{j}

in other words

H=-J{\sum}_{\langle i,j\rangle}\cos(\theta_i-\theta_j)

where the sum runs over all pairs of nearest neighbour spins, \mathbf{S}, and where J is the coupling constant.

Random field XY model (RFXY)[edit]

XY universality class[edit]

(see: XY universality class)

See also[edit]


Related reading