Interfacial tuning of perpendicular magnetic anisotropy and spin magnetic moment in CoFe/Pd multilayers

Abstract

We report on a strong perpendicular magnetic anisotropy in [CoFe 0.4nm/Pd t] 6 (t = 1.0-2.0 nm) multilayers fabricated by DC sputtering in a ultrahigh vacuum chamber. Saturation magnetization, M s , and uniaxial anisotropy, K u , of the multilayers decrease with increasing the spacing thickness, with a M s of 155 emu/cc and a K u of 1.14×10 5 J/m 3 at a spacing thickness of t = 2 nm. X-ray absorption spectroscopy and X-ray magnetic circular dichroism measurements reveal that spin and orbital magnetic moments of Co and Fe in CoFe film decrease as function of Pd thickness, indicating the major contribution of surface/interfacial magnetism to the magnetic properties of the film.

Soft x-ray ptychography studies of nanoscale magnetic and structural correlations in thin SmCo5 films

“…D can range from a few nanometers for hard magnets, such as Nd 2 Fe 14 B, 30 to tens of nanometers for soft magnetic materials, e.g., permalloy (Fe 20 Ni 80 ) 30 or CoFe/Pd multilayers. 31 The in-plane and out-of-plane magnetization loops shown in Fig. 1(a) for the SmCo 5 thin film studied here allow J and K U to be estimated and the actual domain wall width is predicted to be $10 nm, in agreement with expectations given our spatial resolution.…”

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

“…35 Additionally, previous studies suggested that these magnetic moments might arise from the magnetic polarization of Pd 4d caused by hybridization with the Co and Fe 3d ions. 8,36 Additionally, the use of nobble metal Pd as spacing layers could bring more benefit to the film if being used in spin-electronic devices because of the long spin-diffusion length of Pd, 37,38 and less structural diffusion to magnetic layers to make a stable PMA owning to high melting temperature of Pd.…”

“…[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.…”

“…With high out-of-plane anisotropy, very thin Bloch-type walls are expected to exist in the films (the wall width can be estimated to be sub-5 nm using the relation 8 with A ≈ 20 pJ/m for CoFeB-based films). 39 By adjusting the thickness of the layer thickness and the number of CoFeB/Pd bilayers, the M s can be reproducibly controlled from very low range (~280 emu/cc) to moderately high 830 emu/cc.…”

MAGNETIC PROPERTIES AND DOMAIN STRUCTURE OF CoFeB/Pd MULTILAYERS WITH PERPENDICULAR MAGNETIC ANISOTROPY

“…Many PMA multilayers have been studied such as Co base: Co/Pt [2,9], Co/Pd [10,11] and CoFe/Pd [12,13], CoPt and FePt [14,15], CoFeB/MgO [3,15,16]. Among these, CoFeB/Pd multilayers are more attractive because they exhibit high spin polarization [17] and moderate saturation magnetization [16], which are essential for reducing the current density required for spin switching.…”