Size-dependent magnetism in nanocrystals of spin-chain α-CoV2O6

作者：Shu, H.; Ouyang, Z. W.^*; Sun, Y. C.; Ruan, M. Y.; Li, J. J.; Yue, X. Y.; Wang, Z. X.; Xia, Z. C.; Rao, G. H.

来源：Journal of Magnetism and Magnetic Materials, 2016, 407: 129-134.

DOI：10.1016/j.jmmm.2016.01.063

• Nanoparticles
• 1/3 magnetization step
• Spin chain

Magnetization and high-field ESR measurements have been performed to study the magnetism of nanocrystals of alpha-CoV206, an Ising spin-chain system without triangular lattice but presenting interesting 1/3 magnetization step. The results demonstrated the antiferromagnetic (AFM) enhancement and gradual suppression of the 1/3 magnetization step in nanoparticle samples. Within the framework of core shell model consisting of the AFM core spins and the uncompensated/disordered shell spins, the AFM enhancement below TN = 13 K is a result of enhanced shell disorder with weak ferromagnetism. This AFM enhancement, along with the suppression of saturation magnetization, results in the suppression of 1/3 magnetization step. Furthermore, the paramagnetism of the shell was confirmed by our high-field ESR measurements. The time-dependent magnetization suggests the presence of spin-glass-like freezing. This is expected for nanoparticles with surface shell disorder with ferromagnetic correlations, but is not expected for bulk material of alpha-CoV206 without spin frustration. These findings demonstrate that size tuning is an effective parameter for controlling the ground state of alpha-CoV206.

• 出版日期2016-6-1
• 单位华中科技大学; 桂林电子科技大学