Recently, thermoinduced magnetization (TiM) has been predicted to lead to ferromagnetic properties in nanoparticles of antiferromagnetic materials below the ordering temperature. Specifically, the susceptibility is found to increase linearly as the temperature is increased. Here, the magnetic properties of linear chains of three-dimensional classical Heisenberg spins are calculated both analytically and using Monte Carlo techniques. TiM is shown to be associated with the ordering of the spins induced by a single-site uniaxial anisotropy, and the per-spin susceptibility is found to be approximately independent of the number of spins in the chain. For large anisotropies, TiM is shown analytically to be associated with the thermal fluctuations of individual spins, in contrast to current theories.
展开▼
