Metastable 1/3 magnetization plateau and memory effects in spin-chain compound α-CoV 2 O 6

We demonstrate the metastable 1/3 magnetization plateau and memory effect in Ising spin-chain system α-CoV 2 O 6 by magnetic relaxation measurements. The metastability of magnetization plateau below 8 K (< T N = 15 K) in the bulk sample can be ascribed to a competition between magnetic, strain, and thermal energies. The memory effect is observed below 8 K in nanocrystals, which is absent in the bulk material. The amazing memory effect can be described by the phenomenological hierarchical model, and its origin is due to spin-glass-like freezing arising from complicated competing interactions associated with core and shell, according the core–shell model of antiferromagnetic nanoparticles.