Magnetic ordering in two-dimensional Heisenberg antiferromagnets with variable interlayer distances

Abstract
We have investigated the finite temperature magnetic ordering in the quasi-two-dimensional Heisenberg antiferromagnetic system (CnH2n+1NH3)2MnCl4 with various chain lengths n. Our results indicate that in long-chain compounds with large interlayer distances, secondary interactions in magnitude besides the exchange interaction, such as the Ising anisotropy and the Dzyaloshinsky-Moriya interaction, play an important role in the magnetic phase transitions.