Antiferromagnet & Néel Order

Controls

Temperature T/J 1.50 Grid size N 20 External field H 0.00 MC speed 10

T/J = 1.50 (T_N ≈ 2.27J)
Néel order |m_AF| = —
Net magnetization = —
Energy/spin = —

Antiferromagnet: nearest-neighbor coupling J>0 prefers anti-alignment. Square lattice divides into two sublattices A and B. Néel order parameter: m_AF = (M_A - M_B)/(N/2). Phase transition at T_N ≈ 2.27J (same as Ising T_c — equivalent by sublattice gauge transform). Above T_N: disordered. Apply field H to see spin-flop transition.