Research On The Magnetoresistance And Switching Behavior Of The Ferromagnetic Tunnel Juctions

With the development of science and technology, the human society has already entered and the information age which takes the computer widespread application as the symbol, people have more and more high expectations for memory capacity of information. The magnetic recording device taking magnetic metal as medium is higher and higher in record density, commercial HDD storage density is generally 20 Gbit/in2 at present, the highest one has already reached 52.3 Gbit/in2, and the memory density of the laboratory has already reached above 1 Tbit/in2. The high storage density must require the device has the high sensitivity inevitably, so the scientific research in this respect is one of the current focuses. At the end of the eighties of last century , Baibich and other scientists found the magnetoresistance effect in the metal multi-layer membrane of the Fe/Cr and called it the Giant Magnetoresistance (GMR ), the spinning valve structure that was developed by Dieny in 1991 on this basis can obtain bigger GMR effect under smaller magnetic field. In 1975 Julliere discovered that the magnetoresistance effect existed in Fe/Ge/Co tunnel junction, known as the Tunnel Magnetoresistance (TMR ). Compared with common multi-layer film of metal, the Magnetic Tunnel Junction structure formed of the ferromagnetic layer / insulating barrier / the ferromagnetic layer have the characteristic of the high hinder, low consumption, high output voltage, which has the extensive application prospect . The present paper used the ion beam sputtering and magnetron sputtering installment to prepare the iron magnetic tunnel-junction structured by the ferromagnetic layer / insulating barrier / the ferromagnetic layer, adopted four probe method to study the electromagnetism characteristic of the tunnel junction, observed the non-linear volt-ampere characteristic in tunnel junction; Studied the influence to the magnetoresistance effect of the tunnel junction that is attributed to the different insulating barrier structure and thickness, found the relation among middle insulating barrier structure and thickness and value of magnetoresistance; Studied the impact on magnetoresistance of the ferromagnetic layer thickness, found that the TMR value will appear the periodic oscillation in the certain scope along with the increase of the ferromagnetic layer thickness; studied the impact on the tunnel magnetoresistance effect of the different annealing condition. Present subject of thesis belongs to the project subsidized by the national natural science fund (project authorization sanction number: 90207014).