EXCHANGE COUPLING IN SPIN-VALVE STRUCTURES CONTAINING AMORPHOUS COFEB

(80)B-20/Cu/(Co0.9Fe0.1)(80)B-20/Ni80Fe20/Fe50Mn50 spin-valve structur es with a different Ni80Fe20 layer thickness were prepared by ion-beam sputtering. Varying the thickness of the Ni80Fe20 layer made it possi ble to control the exchange coupling between the Fe50Mn50 and amorphou s CoFeB layers. When no Ni80Fe20 layer was inserted, the exchange coup ling was responsible for increasing the coercivity of the a-CoFeB laye rs. With increasing Ni80Fe20 layer thickness, the biasing fields of th e Fe50Mn50 layer increased from 0 to 125 Oe. The critical Ni80Fe20 thi ckness, above which the biasing effect was observed, was experimentall y estimated to be 2 nm. (C) 1997 American Institute of Physics.