Spin-glassy behavior and exchange bias effect of hexagonal YMnO3 nanoparticles fabricated by hydrothermal process

Magnetic properties of hexagonal YMnO3 nanoparticles were systematically investigated. It is found that zero-field cooled and field-cooled magnetization display divergences at low temperature and a spin-glass temperature of T-SG of 43 K are undergone. The thermoremanent magnetization further confirms the spin-glass feature of the YMnO3, which is related to the surface effects resulting in uncompensated spin and suppression of antiferromagnetic order. In particular, the exchange-bias effect is attributed to an exchange coupling between an antiferromagnetic core and the spin-glassy shell or ferromagnetic surface spins of the nanoparticles, which depends on the cooling field, is very interesting for nanomagnetic devices applications. (C) 2010 American Institute of Physics. [doi:10.1063/1.3296323]