Phase transformation and magnetic hardening in electrodeposited, equiatomic Fe–Pt films

Liang, Defu; Mallett, Jonathan J.; Zangari, Giovanni

doi:10.1016/j.electacta.2010.02.074

Cited by 12 publications

(9 citation statements)

References 16 publications

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“…• C. [9][10][11][12] The major disadvantage for use of these materials in BPM is high annealing temperature, which can deteriorate the thermal stability of the whole stack in BPM, i.e. substrate, SUL, under layer and magnetic layer.…”

mentioning

confidence: 99%

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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confidence: 99%

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 as deposited Pt rich films exhibit an fcc structure and Fe rich films exhibit a bcc structure. 12 As mentioned above, the hydrogen evolution, the formation of Fe hydroxides and other problems come out in FePt electrodeposition from aqueous baths. [4][5][6][7] We have recently developed a novel electrolytes to get a more compact and non-staining Fe/Pt multilayers from nonaqueous electrolyte.…”

Section: Introductionmentioning

confidence: 96%

FePt magnetic multilayers electrodeposited from non-aqueous liquids

Zhou

Wei²,

Lou

et al. 2013

Surface Engineering

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FePt magnetic multilayers were pulse electrodeposited from the mixture of ammonium hexachloroplatinate and iron dichloride in ionic liquids based on glycol (EG) and 1-ethyl-3-methylimidazolium chloride (EMIC). The chelate effect and electrochemical behaviour of the EMIC with the ions were determined by ultraviolet-visible spectra and cyclic voltammetry respectively. The iron atomic content in the FePt films ranged from 0?4 to 81?0 at-% when deposition potentials changed from 1?0 to 22?0 V(Ag/AgCl) in electrodeposition system with the EG (50 mL), ammonium hexachloroplatinate (25 mM L 21 ), iron dichloride (175 mM L 21 ) and EMIC (25 mM L 21 ) at 393 K. Fe 50 Pt 50 thin films with smooth surface (50 at-% iron layer in FePt film) and the multilayer cross-section were obtained. Fct structural FePt multilayer was obtained based on X-ray diffraction pattern. Magnetic hysteresis loops showed that the multilayer possessed a magnetic anisotropic behaviour.

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“…% oxygen and formed a disordered cubic structure (FCC) in the as-deposited state 16 ; suitable alloy compositions could be transformed to L1 0 ordered structures at relatively low temperature (450C), exhibiting up to about 14 kOe coercivity 17,18 ; compositionally graded multilayers could also be obtained by modulating the potential waveform, which facilitated magnetic hardening at low total thickness 19 . Electrodeposition of magnetic films provides unique advantages with respect to vacuum deposition methods, mainly due to the possibility to perform additive fabrication of patterned films by through-mask plating 20 , which makes possible the precise reproduction of lithographic patterns even at 0018 This article has been accepted for publication in a future issue of this journal, but has not been fully edited.…”

Section: Introductionmentioning

confidence: 99%

Structure, Magnetic Properties, and Phase Transformations in Electrodeposited Fe-Rich Fe–Pt Films

Liang

Zangari

2015

IEEE Trans. Magn.

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Fe rich Fe-Pt films with 56 to 75 at.% Fe are electrodeposited from an alkaline solution. A FCC (111) texture is clearly observed for as-deposited films with less than 62 at. % Fe, while a BCC (110) orientation is seen for higher Fe fraction. After annealing in forming gas for one hour at or above 400C, a transformation to a face centered tetragonal FCT L1 0 phase was observed below 62 Fe at.%. With increasing Fe content, the annealed films show a texture change from (200) to (002); films with less than 72% Fe show coercivity ~7 kOe while films with Fe above that value show small coercivity.Of particular interest are the 75 at.% films; these show a FCT structure after annealing at or above 450C, which differs from the L1 0 structure and is characterized by low anisotropy; in contrast, a relatively high out of plane coercivity (1-3 kOe) is observed in 75 at. % films in the as-deposited or annealed conditions up to 350C. 0018-9464 (c)

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Phase transformation and magnetic hardening in electrodeposited, equiatomic Fe–Pt films

Cited by 12 publications

References 16 publications

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

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

FePt magnetic multilayers electrodeposited from non-aqueous liquids

Structure, Magnetic Properties, and Phase Transformations in Electrodeposited Fe-Rich Fe–Pt Films

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