Preparation And Studies Of Properties Of Mn-Zn Ferrite Thin Films

Soft magnetic ferrite is the strongest branch of the ferrite development.At present,soft magnetic ferrite has been used in many areas such as telecommunication, instruments and meters,self-control,computer technology and so on.Soft magnetic ferrite has become a kind of magnetic materials which are the most abundant and common. To be smaller and more integrated is the direction of electronic components' development in future,so bulk materials will not satify the requirements. Magnetic thin films with high resistivity were advanced for applications to micro-inductors and micro-transformers. Metal alloys have high conductivity and serious eddy currency loss for high frequencies so that their applications are limited.Thus,soft magnetic ferrite thin film with high resistivity is a valuable media for film inductor.MnZn ferrite film has the good character of high resistivity,good quality at high frequency and good performance of soft magnetism.But, in the preparation there are many factors that are not easy to control,MnZn ferrite is sensible to its environment.In this paper,I have got the best conditions in preparation.To analyse the results of the samples,low Hc and Ms have been observed.Generally speaking,the He of thin film is higher than that of bulk,but in this paper the lowest He of Mn_0.5Zn_0.5Fe₂O₄ thin film on MgO(100) decreases to 27 Oe which is a better value of rf sputtering preparation.Low Hc also is observed on Si and other substrates.From the SEM,the crystal grain size is smaller than 20nm.Exchange coupled interaction is used to explain the results.Furthermore,some other possible reasons which are stress,defect and so on are discussed.The low Ms is not expected,but the results in this paper may be caused by some reasons:(1),through the XRD,I conclude there may be some amorphous states in the films.(2),there may be dead layers on the surface of crystal grains.(3),Mn²⁺ was oxidized to Mn³⁺ and Mn³⁺ has a relatively higher crystal field stabilization energy for octahedral coordination.Thus it tends to stay at theoctahedral B site.The magnetic moment of Mn3+ is smaller than Mn2+.So it leads to decrease the total magnetic momen and thus the Ms.From the data of the Mossbauer spectra,we can conclude some informational) The data certificates that Zn2+ tends to occupy the A site,with the increase of the content of Zn2+,it will lead to decrease the total magnetic moment and the hyperfine field Hhf .(2) The magnetic moment is not parallel to the film surface strictly,there is an angle which is about 20 degree to 30 degree between the magnetic moment and the surface of the films.