THE EFFECT OF COBALT CONTENT ON MAGNETIC PROPERTIES OF CoFe ALLOYS

Widia Nursiyanto,M Alfatun N,L Rohman,E Purwandari

doi:10.21009/spektra.052.01

Widia Nursiyanto, M Alfatun N + Show 2 more

Open Access

https://doi.org/10.21009/spektra.052.01

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Abstract

Hard Disk Drive (HDD) as a data storage device when operated with high temperatures (around 66oC), its function will be constrained. The CoFe alloys have a large coercivity field and can be patterned in very small sizes that are suitable for HDD devices. In this study, Co1-x Fex cube alloy was used (x = 0.25; 0.30; 0.50; 0.75). Samples were treated with temperature changes to get the Curie temperature. The coercivity field value is obtained by giving the external field and temperature below Curie temperature and also above Curie temperature to the samples. The VAMPIRE software is a micromagnetic simulation program based on atomistic models. The results showed that Curie’s temperature decreased when Co content increased. The composition of Co0.25 Fe0.75 has the highest Curie temperature that is equal to 1075 K. The temperature Curie is not affected by the size of the cube. When the sample is given a temperature rise below the Curie temperature, the value of the coercivity field decreases. The value of the coercivity field is very difficult to determine when the temperature used is above the Curie temperature. The percentage of composition does not affect the coercivity field value. Therefore, cube-shaped CoFe material is very suitable for use as a material data storage device operated at temperatures below the Curie.

Highlights

Hard disk drive (HDD) magnetic recording media has problems in their use related to the physical characteristics of materials, such as high-temperature resistance and the occurrence of unstable data stored conditions due to super-paramagnetic effects
Super-paramagnetic effects are properties that appear on nano-sized materials and one-order magnetic domains, so the particles will be very reactive to external magnetic fields [1]
If the HDD always works at overheat temperatures or even exceeds it, it can make the HDD work slower, and the worst possibility will shorten the HDD’s life due to permanent damage

Summary

INTRODUCTION

Hard disk drive (HDD) magnetic recording media has problems in their use related to the physical characteristics of materials, such as high-temperature resistance and the occurrence of unstable data stored conditions due to super-paramagnetic effects. If the temperature rises in a state of decreased magnetization energy, there will be a process of demagnetization and a change in the orientation of the magnetization [2] This results in unstable data stored information, and the worst possible damage will occur. The CoFe alloys are one example of ferromagnetic alloys suitable for HDD materials that can improve the magnetic properties of materials with varying degrees of quality Each of these quality levels differs in their composition and heating treatment to obtain the properties of ferromagnetic materials that are appropriate to their needs or use. To gain an understanding of the macroscopic properties of CoFe magnetic materials such as anisotropic surfaces, spin dynamics, and microstructural effects, it can be done with a Vampire micromagnetic simulation program, an open-source software that uses atomic modeling based on the classic Hamiltonian spin and the Landau-Lifshitz-Gilbert (LLG) equation. [9,10]

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