High-coercivity CoFe2O4 thin films on Si substrates by sol-gel

CoFe2O4 (CFO) thin films with high coercivity Hc are desirable in applications. The difficulty in achieving large-area CFO thin films with high coercivity by sol-gel has hindered the development of CFO thin films. Herein, polycrystalline CFO thin films with the room temperature out-of-plane and in-plane coercivity He respectively reached 5.9 and 3.6 kOe has been achieved on the silicon substrate by sol-gel. The room temperature maximum magnetic energy product (BH)(max) and remanence ratio M-r/M-s are of 1.66 MG Oe and 0.58 respectively, which are also the largest values amongst the CFO thin films prepared by solution methods. At the same time, annealing temperature and thickness effects on the Hc, (BH)(max) and M-r/M-s of the derived CFO thin films have been investigated. It is observed that grain size and residual tensile strain in the derived films play an important role in the variations of He and M-r/M-s. These results will provide an effective route for fabricating larger-areahigh-coercivity CFO thin films with low-cost by sol-gel on silicon wafers. (C) 2016 Elsevier B.V. All rights reserved.