Magnetization process of nanoscale iron cluster

Low-temperature magnetization process of the nanoscale iron cluster in line arly sweeped fields is investigated by a numerical analysis of time-depende nt Schrodinger equation and the quantum master equation. We introduce an ef fective basis method extracting important states, by which we can obtain th e magnetization process effectively. We investigate the structure of the fi eld derivative of the magnetization. We find out that the antisymmetric int eraction determined from the lattice structure reproduces well the experime ntal results of the iron magnets and that this interaction plays an importa nt role in the iron cluster. Deviations from the adiabatic process are also studied. In the fast sweeping case, our calculations indicate that the non adiabatic transition dominantly occurs at the level crossing for the lowest field. In slow sweeping case, due to the influence of the thermal environm ent to the spin system, the field derivative of the magnetization shows an asymmetric behavior, the magnetic Fohn effect, which explains the substruct ure of the experimental results in the pulsed field.