Magnetic and Structural Characterization of Permalloy (Ni79Fe21) Thin Films with Uniaxial Magnetic Anisotropy

Öz

In this study, the structural and magnetic properties of permalloy thin films with thicknesses varying from 4 to 20 nm on Si (100) / SiO2 (~ 200 nm) substrate were investigated. Permalloy thin films were prepared in a high vacuum chamber using the oblique angle magnetron sputtering technique. From the in-situ X-ray photoelectron spectroscopy measurements, the alloy composition ratio of permalloy was found as 21% Fe and 79% Ni. X-ray diffraction and reflectivity measurements showed that permalloy films grew in (111) orientation with low surface roughness and at the nominal thicknesses. Magnetic properties were investigated using ferromagnetic resonance (FMR) and vibrating sample magnetometry (VSM) techniques. In-plane uniaxial magnetic anisotropy was observed in the films due to the oblique deposition used in film preparation. Experimental FMR data were simulated by writing a computer code using the free energy minimization method according to the magnetization direction, and thus these uniaxial anisotropy constants of the films were determined. In addition, variations of magnetic properties such as coercive field and anisotropy field depending on thickness are discussed.

Anahtar Kelimeler

• Permalloy thin film
• magnetic oblique anisotropy
• anisotropic magneto resistance

Tek-eksenli Manyetik Anizotropiye Sahip Permalloy (Ni79Fe21) İnce Filmlerin Manyetik ve Yapısal Karakterizasyonu

Öz

Bu çalışmada, Si(100)/SiO2(~200 nm) alttaş üzerine 4 - 20 nm arasında değişen kalınlıklarda büyütülen permalloy ince filmlerin yapısal ve manyetik özellikleri araştırılmıştır. Permalloy ince filmler eğik açılı magnetron saçtırma tekniği kullanılarak yüksek vakumlu odada hazırlandı. X-ışını foto-elektron spektroskopisi ölçüm sonuçlarından, permalloyun alaşım komposizyonu oranı %21 Fe ve %79 Ni olarak bulundu. X-ışını kırınım ve yansıma ölçümleri, permalloy filmlerinin (111) yönünde, düşük yüzey pürüzlülüğüne sahip ve nominal kalınlıklarda büyüdüğünü gösterdi. Elde edilen ince filmlerin manyetik özellikleri ferromanyetik rezonans (FMR) ve titreşimli örnek manyetometresi (VSM) teknikleri kullanılarak araştırıldı. Film hazırlamada kullanılan eğik biriktirme nedeniyle, filmlerde düzlem içi tek-eksenli manyetik anizotropi gözlemlendi. Mıknatıslanma yönüne göre serbest enerji minimizasyonu yöntemini kullanan bir bilgisayar kodu yazılarak deneysel FMR verileri simule edildi ve bu sayede filmlerin tek eksenli anizotropi sabitleri belirlendi. Ayrıca, zorlayıcı alan ve anizotropi alanı gibi manyetik özelliklerin kalınlığa bağlı olarak değişimleri tartışıldı.

Anahtar Kelimeler

• Permalloy ince film
• manyetik oblige anizotropi
• anizotropik manyeto direnç

Kaynakça

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