Sputtered high perpendicular magnetic anisotropy CoPt thin film on flexible substrate at low temperature

Glemarie C Hermosa,An-Cheng Sun

doi:10.1063/1.5129915

Abstract

In this study, CoPt alloy thin films with alternative sputtering of 0.4 nm-Co and 0.5 nm-Pt layers, [Co0.4/Pt0.5]n, on Pt underlayers were sputtered on rigid glass and soft PI (Polyimide) substrates at 100°C. The effects of repetition (n) of the [Co0.4/Pt0.5]n films on the magnetic properties and microstructures of [Co0.4/Pt0.5]n films were investigated. Results showed that [Co0.4/Pt0.5]4 film had a high perpendicular magnetic anisotropy (PMA (S⊥&gt;0.98)) and a magnetocrystalline anisotropy constant (Ku∼1.12×107 erg/cm3), which were close to the properties of L11-CoPt film prepared at higher temperatures (∼300°C) as seen in previous works. Increasing repetition also increased residual stress and further reduced perpendicular magnetic properties. Thus, better magnetic properties would be obtained in the thinner case. The outstanding PMA properties of CoPt film still well kept as the rigid glass was replaced by flexible PI substrate. In this work, perpendicular magnetic CoPt film could be prepared at lower temperatures (∼100°C) on soft PI substrate. It strongly enhanced low temperature applications of hard magnetic alloy thin films, such as magnetic electronic components with high Ku and PMA on flexible substrate.

Highlights

In order to further reduce the size of magnetic alloy thin films in electronic components with stable magnetic performance, a magnetic film with a high magnetocrystalline anisotropy constant (Ku), high perpendicular magnetic anisotropy (PMA), and good chemical corrosion resistance is necessary
The CoPt looks like well capped on Pt columns by epitaxial growth and that the PMA of [Co0.4/Pt0.5]4 magnetic film was found on PI flexible substrate
PMA CoPt prepared on rigid glass and flexible Pt substrates at lower temperature 100○C

Summary

Introduction

In order to further reduce the size of magnetic alloy thin films in electronic components with stable magnetic performance, a magnetic film with a high magnetocrystalline anisotropy constant (Ku), high perpendicular magnetic anisotropy (PMA), and good chemical corrosion resistance is necessary.1 According to the StonerWohlfarth model, it is believed that when the ratio of KuV/kBT is greater than 60, it is certain that the product will be used for more than a decade.1,2 a high Ku material with a low formation temperature has attracted much attention because it reduces cost and inhibits interlayer diffusion, thereby further increasing the potential in application in magnetic recording media, spintronic devices, nano-electro-mechanical systems (NEMS), etc. A low formation temperature is helpful in depositing magnetic film on soft substrate for flexible electronic devices. Structure has attracted a great deal of attention in the past two decades due to its large Ku (5×107 erg/cm3), high PMA, and good chemical corrosion resistance.3–9 the formation temperature of L10 FePt film is usually higher than 450○C, which is a drawback in the soft substrate process.1–4 A CoPt film with a rhombohedral L11 structure has similar magnetic properties to L10 FePt film, but it could be fabricated at 300○C, which is regarded as a potential candidate to replace the hard magnetic films people use at present.10–25 Recently, L11 CoPt film was successfully deposited on an amorphous glass substrate with Pt(111)12,18,20 and Ru(0002)21 serving as the underlayers.

Results

Conclusion