Surface and Microstructure Analysis of CoCrPt Film on RuCoCrX (X = Ti, Re) Intermediate Layers

Jai-Lin Tsai,Ting-Wei Hsu,Shi-Min Weng,Jyun-You Chen,Cheng Dai

doi:10.3390/cryst10040263

Abstract

The microstructural and magnetic properties of perpendicular anisotropic CoCrPt films deposited on Ru or RuCoCrX (X = Ti, Re) intermediate layers were studied. The c-axis of CoCrPt grains were promoted by (0002) textured RuCoCr, and RuCoCrX (X = Ti, Re) intermediate layers due to smaller lattice misfit as compared to Ru. The narrower rocking width (Δθ50 = 3.76°) in RuCoCrRe intermediate layer and CoCrPt shows higher out of plane coercivity (Hc = 6.2 kOe), magnetic anisotropy constant (Ku = 6.2 × 106 erg/cm3) and nucleation field (HN = −2.8kOe) as compared to the Ru intermediate layer (Hc = 5.4 kOe, Ku = 5.9 × 106 erg/cm3, HN = −1.6 kOe). The partial intergranular exchange decoupling of CoCrPt grains was observed. The grain boundaries oxides were formed by the residual oxygen in targets and sputtering processes. The minor Cr2O3, CoO, TiO2, ReO3 oxides were investigated by surface analysis. Due to the minor oxides and Cr segregation at grains boundaries, the CoCrPt films present high coercivity. Samples CoCrPt/RuCoCr and CoCrPt/RuCoCrTi present a minimum at 45° but the values are much higher than the ideal Stoner-Wohlfarth theoretical value 0.5 which could be due to fewer natural oxides for magnetic grains separation. In sample CoCrPt/RuCoCrRe, there is an increase of intergranular interaction as indicated by the large asymmetry and the shift of the minimum at lower angles.

Highlights

The CoCrPt perpendicular magnetic anisotropy thin films have been applied in current perpendicular magnetic recording media for long periods of time but are still required to improve the properties in the near future [1,2,3,4,5,6,7,8,9,10,11,12,13,14]
Ordered L10 -FePt with higher perpendicular anisotropy has been promised for future ultra-high density heat-assisted magnetic recording media [15,16,17], improvements of the intermediate, exchange coupling- and capping-layer are needed to optimize the magnetic properties and microstructure of CoCrPt-oxide granular films for next- generation devices
We propose the nonmagnetic RuCoCrX (X = Ti, Re) to modify the crystallinity and microstructure of the current use Ru and RuCoCr intermediate layer

Summary

Introduction

The CoCrPt (oxides) perpendicular magnetic anisotropy thin films have been applied in current perpendicular magnetic recording media for long periods of time but are still required to improve the properties in the near future [1,2,3,4,5,6,7,8,9,10,11,12,13,14]. Ordered L10 -FePt with higher perpendicular anisotropy has been promised for future ultra-high density heat-assisted magnetic recording media [15,16,17], improvements of the intermediate-, exchange coupling- and capping-layer are needed to optimize the magnetic properties and microstructure of CoCrPt-oxide granular films for next- generation devices.

Methods

Results

Conclusion