Single-Chain Magnets and Related Systems

In this chapter, the static and dynamic magnetic properties of single-chain magnets and related systems are reviewed. We will particularly focus on the so-called Ising limit for which the magnetic anisotropy energy is much larger than the energy of the intrachain exchange interactions. The simple regular chain of ferromagnetically coupled spins will be first described. Static properties will be summarized to introduce the dominant role of domain walls at low temperature. The slow relaxation of the magnetization will be then discussed using a stochastic description. The deduced dynamic critical behavior will be analyzed in detail to explain the observed magnet behavior. In particular, the effect of applying a magnetic field, often ignored in the literature, will be discussed. Then, more complicated structures including chains of antiferromagnetically coupled magnetic sites will be discussed. Finally, the importance of interchain couplings will be introduced to discriminate between a "real" single-chain magnet and a sample presenting both a magnet-type property and a three-dimensional antiferromagnetic ordered state at low temperature.