Seed Layer Effect on the Magnetic Properties of Ultrathin Co/Pt Multilayers With Perpendicular Magnetic Anisotropy

Perpendicular magnetic anisotropy of Co\Pt bilayers on ALD HfO2

“…Below t c , the K eff saturates at 0.25 6 0.03 mJ/m 2 , likely due to the decrease of interfacial anisotropy ascribed to the degradation of the interfaces when the Co thickness decreases. 39,40 This is comparable to values reported in the literature for similar Co-Pt thin film stacks, 3,4 which are on the order of 0.3-0.32 mJ/m 2 . An increased annealing temperature has been reported to decrease the K eff .…”

“…1 Co\Pt bilayers and superlattices deposited on crystalline templates show PMA as deposited. 2 The saturation magnetization of Co\Pt multilayers on crystalline templates increases (from the value of bulk Co, 1446 kA/m) with decreasing Co thicknesses to values ranging between 1600 and 1850 kA/m for films with the Co thickness of 5 Å , 3,4 depending on the annealing conditions and the template material. The effective anisotropy energy for such films is reportedly between 0.3 and 0.32 mJ/m 2 /interface 3,5 in the PMA regime.…”

“…These values are reported for Co\Pt multilayers with the strong (111) texture and are dependent on the Co and Pt thicknesses, 3,5 the sharpness of the Co\Pt interface, 6,7 the annealing conditions, and the crystallinity of the template. 4 HfO 2 on the other hand is amorphous. Co\Pt bilayer structures have already been studied on other amorphous oxides like SiO 2 by Nistor et al 8 They report that an annealing temperature from 250 C to 400 C can modify the Magnetic Anisotropy (MA) of a thin Co film from in-plane (IP) to perpendicular (PMA).…”

“…[11][12][13] Improving the crystallinity of the seed layer can significantly increase the magnetic anisotropy energy K eff at a given annealing temperature 11 as well as the critical temperature. 4,11 K eff is an important figure of merit for Voltage Control of Magnetic Anisotropy (VCMA) in ferromagnetic materials, which has attracted increasing attention since the first experimental evidence of the phenomenon in liquid electrolytes by Weisheit et al…”

Seed layer impact on structural and magnetic properties of [Co/Ni] multilayers with perpendicular magnetic anisotropy

“…Co-based PMA multilayers [Co/X] (X = Pt, Pd) have received a lot of attention for their potential application in STT-MRAM, especially as SAF materials [4][5][6] . The PMA of these multilayers comes from the interface of a) Electronic mail: Enlong.Liu@imec.be.…”