UV irradiations enhance anisotropy of ZnO nanorods in crystal growth and ferromagnetism

The crystalline growth of the preferred orientation in the ZnO nanorods will be profoundly enhanced as we irradiate a specific wave length of ultra-violate (UV) during the sample fabrication. The specific UV photon energy is equivalent to the ZnO band gap. Both samples, with and without UV irradiated undoped nanorods, exhibit the anisotropic ferromagnetism. The electric polarization yields the ferromagnetic anisotropy along the c-axis, which suppresses the ferromagnetism in the same polarized direction and creates a similar multiferroic characteristic. Besides, the specific UV irradiation significantly enhances the ferromagnetic anisotropy. - Highlights: • A specific UV irradiation makes an enhancement in crystalline growth as well as in ferromagnetism. • The magnetization in our UV irradiated ZnO nanorods is very preferring to polarize along the in-plane direction. • The ferromagnetic ZnO nanorods behave as a multiferroics