Preisach analysis of reversible magnetization in SmCo/Fe films

SmCo(50 nm)/Fe(y nm) bilayers (y=0, 2.5, 5, 20) were prepared by magnetron sputtering on Si substrates. The films showed coercivities in the range 1.5 -14 kOe as well as remanence enhancement, characteristic of exchange-couple d systems. Henkel plots for these bilayers showed that the demagnetizing in teractions increase as the thickness of the Fe layer increases. For each fi lm, a set of minor loops was measured in order to determine the Preisach di stributions. With suitable analytic forms for these distributions, we obtai ned a description of the experimental data for the major loops, the minor l oops and recoil curves. The comparison with experiment is excellent. From t he moving Preisach model we have determined the evolution of the reversible and irreversible magnetization components during the magnetization and dem agnetization processes. The most important source of M-rev is the reversibl e rotation of the magnetization in the grains of the SmCo layer. The soft F e layer, when well coupled to the SmCo layer, contributes mainly to M-rev, but is also an important source of M-irr. (C) 2000 American Institute of Ph ysics. [S0021-8979(00)63508-9].