When the film thickness is less than 10 nm, thermal energy interrupts the magnetic moment orientation due to small grain size, which shows superparamagnetic effect. With increasing film thickness, spinel structure LY2603618 chemical structure is formed and crystallite size increases, which results in the decrease in the full width at half maximum of the X-ray spectral peaks and the increase of M s. Figure 4 TEM images of the 500-nm ferrite film. Dark-field cross-section image (a) and the HRTEM
image (b). Conclusions Ni ferrite films with different thicknesses were fabricated under RT. Structure and magnetic selleck properties of Ni ferrite films were investigated as functions of thickness: the 10-nm film exhibits superparamagnetism; M s increases monotonically, while H c first increases then INCB28060 cost decreases as the film thickness increases. The SEM and TEM images were taken to investigate the underlying magnetic mechanism. A disordered layer at the bottom of the ferrite layer can be seen in the TEM image; this layer may probably be responsible for the superparamagnetic behavior of the 10-nm film. Acknowledgments This work is supported by
the National Basic Research Program of China (grant no. 2012CB933101), the National Science Fund for Distinguished Young Scholars (grant no. 50925103), the Key Grant Project of Chinese Ministry of Education (grant no. 309027), the National Natural Science Foundation of China (grant no. 11034004 and no. 50902064), and the Fundamental Research Funds for Central Universities (lzujbky-2012-31). References 1. Ramos A, Matzen S, Moussy J-B, Ott F, Viret M: Artificial antiphase boundary at the interface of ferrimagnetic spinel bilayers. Phys Rev B 2009, 79:014401.CrossRef 2. Masoudpanah SM, Seyyed Ebrahimi SA, Ong CK: Magnetic properties of strontium
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