Spin‐Wave Theory on Quasi‐One‐Dimensional Heisenberg Antiferromagnets

The low‐temperature of quasi‐one‐dimensional Heisenberg antiferromagnets with ferromagnetic coupling between nerest‐neighbor spins within a chain and antiferromagnetic couplng between nearest‐neighbor spins withina chain and antiferromagnetic coupling between chains are studied by the spin‐wave theory. The effects of interchain coupoling on the ground state energy, sublattice magnetization, and perpendicular susceptibility at zero temperture are calculated numerically. At low temperatures, asympototic expressions of sublattice magnetization, internal energy, magnetic specific heat, parallel and perpendicular susceptibilities are given as functions of temperature and interchain coupling strength within tow sub‐temerature regions. It is found that if interchain coupling is weak, with increasing temperature the properties of the system change from threedimensional behavior (Δm ∝ T2, ΔE ∝T4, Cm ∝ T3, X∥ ∝ T5/2, ΔX⊥ ∝ T2) To quasi‐one‐dimensional bahavior (Δm ∝ T, ΔE ∝ T3/2, Cm ∝ T1/2, X∥ ∝ T3/2, ΔX⊥ ∝ T).