With a thin Co layer inserted into the L10-FePt(3 nm)/Fe(2 nm) ECC structure, a large reduction of coercivity is observed in such a graded trilayer, with a minimum value of 1.45 kOe when the Co thickness is 2 nm, similar to that of FePt(3 nm)/Fe(4 nm). The magnetization reversal in both FePt/Fe and FePt/Co/Fe structures is carefully studied by the vector vibrating sample magnetometer. The nucleation, wall compression, and irreversible magnetization rotation are discussed.
Bibliographical noteFunding Information:
This work is supported by the NSF of China (Grant Nos. 51071046, 61078030, and 11074046) and the National Basic Research Program of China (2009CB929201). The authors thank Professor J. Du in NJU for V-VSM measurements. FIG. 1. (Color online) The XRD θ -2 θ scans of FePt based films: (a) FePt; (b) FePt/Fe (2 nm); (c) FePt/Fe (5 nm); (d) FePt/Co (2 nm); and (e) FePt/Co(2 nm)/Fe(2 nm). FePt peaks are labeled by the index. FIG. 2. (Color online) The coercivity dependence on the soft layer thickness for two series of samples FePt(3 nm)/Fe (t S nm) and FePt(3 nm)/Co[(t S -2)nm)/Fe(2 nm)]. The star is the coercivity of FePt(3 nm)/Co(2 nm). The first point of FePt/Co/Fe is FePt/Fe(2 nm). FIG. 3. (Color online) The M X (full square) and M Y (line) loops of (a) FePt/Fe(2 nm), (b) FePt/Co(2 nm)/Fe(2 nm), and (c) FePt/Co(2 nm)/Fe(2 nm) with the magnetic field applied at 45° tilted from the film normal. The black curves (halves of the loops) represent the magnetization dependence on the applied field from positive saturation to negative saturation, and the red curves from negative saturation to positive saturation. The arrows mark the loop’s direction. FIG. 4. (Color online) The schematic diagram of the magnetization reversal in L 1 0 FePt/Co(2 nm)/Fe(2 nm) film: (a) saturation state, (b) nucleation, (c) remanence state, and (d) critical point of magnetization reversal.