Magnetization Dynamics and Damping for <i>L</i>1₀-FePd Thin Films with Perpendicular Magnetic Anisotropy

Abstract

Magnetization dynamics and damping for FePd films were investigated using the all-optical time-resolved magneto-optical Kerr effect. We deposited 16-nm-thick FePd thin films on a single crystal MgO(001) substrate. Both in-plane magnetic anisotropy and perpendicular magnetic anisotropy (PMA) FePd films were fabricated using the magnetron sputtering method at various substrate temperatures T s . The dependencies of magnetization dynamics on the external magnetic field angle at fixed external magnetic field strengths were analyzed. The effective damping constant, α eff , for FePd films with PMA exhibited anisotropy, whereas the α eff for FePd with in-plane magnetic anisotropy did not depend significantly on the field angle. A uniaxial crystalline magnetic anisotropy constant, K u1 , of 11 Merg/cm 3 and a minimum for α eff of 0.007 were observed for film prepared at T s = 200 • C. This α eff value was much smaller than that for other Fe-and Co-based materials with large PMA such as L1 0 -FePt alloy, Co/Pt(Pd) multilayers.

Enhancement of tunneling magnetoresistance by inserting a diffusion barrier in L1-FePd perpendicular magnetic tunnel junctions

“…[18][19][20][21] L1 0 -FePd has recently been experimentally verified to have a $ 0.002 and K u $ 1.3-1.4 Â 10 7 erg/cm 3 (Refs. 2,22,and 23) and, as reported by Naganuma et al, 24 has demonstrated a 27.0% room temperature (RT) tunnel magnetoresistance (TMR) ratio in partially perpendicular MTJs (p-MTJs) with an in-plane reference layer.…”

Spintronics technology and device development

“…By this technique, a TMR ratio of up to 604% has been achieved at room temperature. 49) The combination of the above two techniques to obtain a higher TMR ratio has been examined. Namely, Heustler alloys with high polarization and MgO are used for the electrodes and barrier layer, respectively, to obtain a synergetic effect.…”

“…The Gilbert damping constant of an L1 0 -ordered FePt alloy is at least 0.04, 63,76) whereas that of an L1 0 -ordered FePd alloy is relatively small (about 0.01). 65) The Gilbert damping constant of CoFeB may be reduced to around 0.01, although it depends on the composition, film formation conditions, and film thickness. 59,67) Recent studies have shown that some materials have the potential to achieve a damping constant of below 0.01 while having a magnetic anisotropy constant of 10 Merg=cm 3 or higher, which has been difficult to realize with conventional material systems.…”

L10 Fe−Pd Synthetic Antiferromagnet through an fcc Ru Spacer Utilized for Perpendicular Magnetic Tunnel Junctions

“…The manganese (Mn)-based Heusler alloys [11][12][13][14][15] and the L1 0 -FePd are promising candidates for satisfying these requirements. Compared with the Mn-based Heusler alloys, the L1 0 -FePd bulk PMA material possesses very attractive properties, such as a large K u (13-14 Merg/cm 3 ) [16,17], a low α (0.002) [18,19], and a low processing temperature (200 o C) [20], which are summarized in Table 1. Furthermore, the switching current density (J c ) for spintronic memory devices, such as STT-MRAM, is a critical parameter, defined by the equation: [21], where J c mainly relates to the damping constant (α), the saturation magnetization (M S ), and the perpendicular anisotropy field (H k ).…”