Studies On The Spin Dependent Transport Properties In Fe/Zno Thin Films

Spintronics is a new field of electronics, which is not based on conduction by electrons or holes as in microelectronics,but on the different transport properties of majority and minority spin eleetrons,and it is the spin degree of freedom not the electric charge carries the information.As a basic subject of spintronies,spin dependent transport phenomena has been well studied in both full-metal and metal-insulator systems as multilayers and granular films and new generation of magnetic storage devices has already been developed.However,there is few reports on the spin dependent transport priorities in metal-semiconductor systems.In this study of the spin dependent transport properties in Fe-ZnO thin films,the wide band semiconductor ZnO,which has been widely used in Photoeleetronics devices because of its transparent and high conduction and typical ferromagnetic metal Fe has been employed to form multilayers.The spin dependent transport phenomena in Fe-ZnO system have been studied and the main works are listed as following:(1)A series of Fe/ZnO multilayers with different Fe and ZnO layers thickness were prepared by DC sputtering method.The magnetic properties,electrical properties and spin dependent transport properties were investigated by vibrating sample magnetometer and magneto-eleetronic measurement system.(2)The magnetic character of the multilayers can be modified by the ZnO layer while the Fe thickness is fixed.(3)The MR for the sample [Fe(1.5nm)/ZnO(2nm)]30is measured. Giant magnetoresistance with a maximum of-2.15%at room temperature and-3.48%at15K were observed. A reasonable fitted result is obtained using MR(H)-0.027*[M(H)/Ms]2.(4)The temperature dependence of resistivity (p) for a series of Fe/ZnO multilayers samples are measured. For temperature lower than130K, the resistance agrees well with the Mott’s theory of variable range hopping conductance (VRH) and the temperature dependence of resistance can be written as:lnp-(To/T)1/2. This indicates an inter-region tunneling conduction mechanism in the sample. The ZnO layers provide a tunneling barrier between the magnetic Fe layers.