Critical Fe thickness for effective coercivity reduction in FePt/Fe exchange-coupled bilayer

▶ We studied the exchange effect and magnetization reversal of FePt/Fe perpendicular exchange-coupled bilayers. ▶ The bilayers with various Fe thicknesses (0-8 nm) were fabricated. ▶ Coercivity reduced dramatically with increase of Fe thickness to 3 nm, was maintained with further increase of Fe thickness. ▶ A maximum coercivity reduction factor of 2.5 was obtained. ▶ The critical Fe thickness for effective coercivity reduction is the exchange length.