Perpendicular Magnetic Anisotropy in CoFeB/Pd Bilayers

Abstract

Perpendicular magnetic anisotropy is observed in ultrathin ( 0.6 nm) amorphous Co 40 Fe 40 B 20 when sputtered on an MgO (001) buffer layer and capped with Pd. The layers are superparamagnetic with a blocking temperature of 230 K, below which they show an exponential temperature dependence of coercivity. Perpendicular magnetic anisotropy is observed in the as-deposited state and the mechanism is different from that of CoFeB/Pt, which requires postannealing. These ultrathin layers could be a model system for studies of electric field effects on magnetic anisotropy.Index Terms-Perpendicular magnetic anisotropy (PMA), thin-film capacitors.

Perpendicular magnetic anisotropy and the magnetization process in CoFeB/Pd multilayer films

“…[2][3][4][5][6][7][8] However, the results in this article (and some recent papers) [26][27][28] have demonstrated that the structural condition is not a necessary criterion for the CoFeB/Pd interfaces. This is presumably a physically interesting aspect for a deep analysis of interfacial magnetic moment and electronic structure of the CoFeB/Pd interfaces by a number of tools, e.g.…”

“…[23][24][25] Recently, PMA in multilayer films using amorphous CoFeB layers and noble metal spacing have been reported. [26][27][28] Several advantages allow considering PMA amorphous CoFeB films as an excellent candidate for spin-transfer torque applications:…”

Variable variance Preisach model for multilayers with perpendicular magnetic anisotropy

“…This is evidence [73] that the anisotropy of a single Pd/CoFeB/Pd multilayer is given by the combination of an in-plane volumetric component K v , and an out-of-plane component K s , which arises from a surface or interface anisotropy present at each CoFeB/Pd interface due to atomic mixing [54,74,75]. This competition eventually leads to the disappearance of the PMA for thicker CoFeB layers, as shown in Fig.…”

Magnetic tunnel junctions using Co/Ni multilayer electrodes with perpendicular magnetic anisotropy

“…20 However, the well established layer by layer growth of the bottom Co/Ni ML on a smooth (111) textured Pt buffer 21 has to be compared with the island-like growth process of the top ML on a Al 2 O 3 oxide barrier. 22 Moreover, the top ML may not be well (111) textured on the amorphous barrier, and it has been found that (100) and (110) grain significantly reduce PMA in Co/Ni ML. 23 The tail of the first magnetization jump is typical of the dipolar interactions (so-called demagnetization field) in PMA film thicker than few nanometers 24 but that a fully anti-parallel state is reached before the second step.…”