Influence of Copper on $А1$ to $L1_{0}$ Phase Transformation in Nanoscale Fe$_{50}$Pt$_{50}$ Films

Yu. M. Makogon, O. P. Pavlova, S. I. Sidorenko, T. I. Verbytska, M. Yu. Verbytska, O. V. Fihurna

National Technical University of Ukraine ‘Igor Sikorsky Kyiv Polytechnic Institute’, 37 Peremohy Ave., UA-03056 Kyiv, Ukraine

Received: 30.09.2014; final version - 21.01.2015. Download: PDF

By the methods of materials science, the effect of intermediate Cu layer with low surface energy ($\cong 1.83$ J/m$^{2}$) (top, intermediate, and underlayer) in [Fe$_{50}$Pt$_{50}$(15 nm)/intermediate Cu(7.5 nm) layer/Fe$_{50}$Pt$_{50}$ (15 nm)]$_{n}$ (where $n = 1, 2$), top Cu(7.5 nm) layer/Fe$_{50}$Pt$_{50}$(15 nm) and Fe$_{50}$Pt$_{50}$(15 nm)/underlayer Cu(7.5 nm) film compositions on SiO$_{2}$(100 nm)/Si(001) substrates on diffusion phase-formation processes and $L1_{0}$ phase formation, its structure, and magnetic properties at annealing in vacuum is studied. The film compositions are prepared by magnetron sputtering on thermally oxidized SiO$_{2}$ layer by thickness of 100 nm on monocrystalline Si(001) substrate. Subsequent heat treatment is carried out at high vacuum of $1.3 \cdot 10^{-3}$ Pa in the 300—900°C temperature range during 30 s at each temperature. As determined, the chemically disordered $A1$(FePt) phase is formed in all as-deposited films. The formation of chemically ordered $L1_{0}$(FePt) phase in [Fe$_{50}$Pt$_{50}$(15 nm)/Сu(7.5 nm) intermediate layer/Fe$_{50}$Pt$_{50}$(15 nm)]$_{n}$ films (where $n = 1, 2$) with intermediate layers takes place during annealing at 700°C and is accompanied by sharp coercivity increase, which also rises after subsequent high-temperature annealing. In the films with top copper layer, the temperature of $L1_{0}$(FePt) phase formation rises up to 900°C. In the films with copper underlayer, the formation of $L1_{0}$(FePt) phase is not detected by X-ray analysis, but small coercivity increasing after annealing within the temperature range of 800—900°C can testify that ordering processes proceed.

Key words: chemically ordered phase $L1_{0}$(FePt), thin films, annealing, coercive force.



PACS: 66.30.Pa, 68.55.jd, 75.50.Ss, 75.50.Vv, 75.70.Ak, 81.40.Ef, 81.40.Rs

Citation: Yu. M. Makogon, O. P. Pavlova, S. I. Sidorenko, T. I. Verbytska, M. Yu. Verbytska, and O. V. Fihurna, Influence of Copper on $А1$ to $L1_{0}$ Phase Transformation in Nanoscale Fe$_{50}$Pt$_{50}$ Films, Metallofiz. Noveishie Tekhnol., 37, No. 4: 487—498 (2015)

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