Large uniaxial magnetic anisotropy by lattice deformation in CoPt∕Ru perpendicular films

Shimatsu, T.; Sato, Hideo; Okazaki, Yoshiaki; Aoi, H.; Muraoka, H.; Nakamura, Y.; Okamoto, Satoshi; Kitakami, Osamu

doi:10.1063/1.2167351

Cited by 42 publications

(22 citation statements)

References 16 publications

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“…It is important to note that it is the growth fault probability, b, which is being shown, and the possible influence of b 0 cannot be determined from these figures. The most compelling correlation is the strong linear trend observed for K u versus c. Such a trend has been reported previously in the literature 21,22 and is qualitatively consistent with bulk measurements of magnetostriction for single crystal cobalt, where a compression …”

Section: -2supporting

confidence: 75%

Magnetic anisotropy and stacking faults in Co and Co84Pt16 epitaxially grown thin films

Sokalski

Laughlin

Zhu

2011

Journal of Applied Physics

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A combined set of experimental and theoretical diffraction studies are performed to evaluate the possible impact of stacking faults on magnetic anisotropy using epitaxially grown Co/Ru and Co 84 Pt 16 /Ru thin films on MgO(111) single crystal substrates. A 3rd nearest neighbor interaction is incorporated into Monte Carlo simulations of faulted film growth used to predict (10.L) diffraction profiles. These are compared with experimental profiles to determine stacking fault content. It is found that stacking fault density decreases with increasing temperature concurrent with an increase in magnetic anisotropy and a compression of the crystallographic lattice parameter,

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Section: -2supporting

confidence: 75%

Magnetic anisotropy and stacking faults in Co and Co84Pt16 epitaxially grown thin films

Sokalski

Laughlin

Zhu

2011

Journal of Applied Physics

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“…4) recorded in the plane (parallel) and out-of-plane (perpendicular) direction clearly show that the CoPt film deposited on Ru seed layer favors hcp phase formation resulting in higher perpendicular coercivity (H c = 1220 Oe) compared to the CoPt film depsited on Cu seed layer (H c = 254 Oe). This result is expected since it is known that a Ru underlayer exhibits an improvement of the microstructure and enhancement of perpendicular anisotropy of CoPt films obtained either by vacuum deposition 21,[24][25][26] or electrodeposition. 16,17,19,21 The dramatic improvement of crystal structure and perpendicular coercivity is illustrated in Fig.…”

Section: Resultsmentioning

confidence: 80%

Electrodeposition of Thin CoPt Films with Very High Perpendicular Anisotropy from Hexachloroplatinate Solution: Effect of Saccharin Additive and Electrode Substrate

Tabaković

Qiu

Dragos

2016

J. Electrochem. Soc.

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The CoPt films with 9.7-91 at% Co and thicknesses of 15-20 nm were obtained from a new designed stable hexachloroplatinate solution at a controlled potential deposition. The effects of the substrate (Ru and Cu) and an organic additive (saccharin) on composition, crystal structure and magnetic properties of the CoPt films were studied. It was demonstrated that a Ru electrode substrate provides well-defined surface for the epitaxial growth of hcp phase, resulting in high perpendicular anisotropy. The addition of saccharin (Sacc) as an organic additive into the plating solution caused a dramatic improvement of the epitaxial growth of CoPt film on the Ru substrate. At the film thickness of interest, for bit-patterned media BPM (15-20 nm), the out-of-plane coercivity showed the highest value of 6700 Oe and the squarness M r /M s ∼1. The areal density of hard disc drives has been increasing at 25-35% per year and now it is approaching to 1 Tb/in 2 . The magnetic crystal grain volume (V) has been decreasing to several cubic nanometers which is near to the thermal instability of granular media, i.e. the superparamagnetic limit. In order to further increase the areal density thermal stability factor, K u V/kT, needs to be kept within 40-60 range. The superparamagnetic effect posses a serious challenge for continuing to increase the areal density and storage capacity of disc drives.1 In order to solve these problems the intensive research and development efforts are currently being carried out worldwide with two major concepts. The first one is to use high magnetoanisotropy (K u ) granular media, i.e. FePt or CoPt alloys, and develop a heat-assisted magnetic recording (HAMR) writer.2 The second is to use conventional perpendicular writer and develop a bit-patterned media (BPM) that effectively increase the grain volume (V).3 Both concepts need to overcome numerous technical challenges in R&D in order to manufacture recording heads with areal density >1 Tb/in 2 and stability over 10 years of data storage.The main idea of BPM technology is that each bit is stored in a single dimensionally defined magnetic switching volume, i.e. dot. Different methods-electron beam lithography (EBL), nanoimprint lithography (NIL), block co-polymer (BCP)-for the fabrication of nano-holes with the long-range ordering and diameter of sub-20 nm corresponding to the density of ∼1 Tdot/in 2 have been demonstrated. 4,5 A typical perpendicular media comprises of a multilayer structure including a substrate covered by a soft magnetic under layer (SUL), an interlayer (seed layer) and hard patterned magnetic layer (BPM). The hard magnetic layer can be a CoPt or FePt electrodeposited alloy of hcp-crystal structure with crystalline grains oriented along the c-axis (the magnetic easy axis) in the direction normal to the film. The important magnetic property at the thickness of interest in BPM (15-20 nm) is high out-of-plane coercivity (H c ) which is largely determined by magnetocrystalline anisotropy and to a lesser extent by shape anisotropy of magneti...

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“…It has been reported that an hcp-CoPt (0 0 1) thin film grown on a Ru (0 0 1) buffer layer exhibits very high K u of the order of 10 7 erg/cm 3 [24,25]. This high K u of CoPt/Ru film does not require substrate heating during film deposition, and the crystal structure of the CoPt/Ru film is a disordered one.…”

Section: Copt/ru Dot Arraymentioning

confidence: 97%

Magnetization behavior of nanomagnets for patterned media application

Okamoto¹,

Kikuchi²,

Kato³

et al. 2008

Journal of Magnetism and Magnetic Materials

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Large uniaxial magnetic anisotropy by lattice deformation in CoPt∕Ru perpendicular films

Cited by 42 publications

References 16 publications

Magnetic anisotropy and stacking faults in Co and Co84Pt16 epitaxially grown thin films

Magnetic anisotropy and stacking faults in Co and Co84Pt16 epitaxially grown thin films

Electrodeposition of Thin CoPt Films with Very High Perpendicular Anisotropy from Hexachloroplatinate Solution: Effect of Saccharin Additive and Electrode Substrate

Magnetization behavior of nanomagnets for patterned media application

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