Pengaruh Lebar Pita Nano Grafena Zig-zag/h-BN Terhadap Karakteristik Spintronik Pada Persambungan Terowongan Magnetik: Studi DFT+NEGF

Fitri, Lailatul (2026) Pengaruh Lebar Pita Nano Grafena Zig-zag/h-BN Terhadap Karakteristik Spintronik Pada Persambungan Terowongan Magnetik: Studi DFT+NEGF. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Persambungan terowongan magnetik (magnetic tunnel junction, MTJ) dikenal melalui efek magnetoresistansi terowongan (tunneling magnetoresistance, TMR) yang berpotensi untuk aplikasi teknologi memori generasi mendatang. MTJ berbasis material kuasi-satu-dimensi menarik untuk dikaji karena dimensinya yang tereduksi sehingga dapat meningkatkan densitas integrasi perangkat. Dalam penelitian ini, pita nano grafena zig-zag digunakan sebagai lapisan feromagnetik, sedangkan heksagonal boron nitrida (h-BN) berperan sebagai lapisan penghalang terowongan. Lebar pita nano divariasikan berdasarkan jumlah rantai zig-zag, yaitu n = 6, 8, 10, dan 12. Karakteristik elektronik dan transpor spin dianalisis melalui perhitungan prinsip pertama berbasis teori fungsional densitas dan formalisme fungsi Green nonekuilibrium. Hasil penelitian menunjukkan bahwa pita nano grafena zig-zag tetap mempertahankan karakter metaliknya pada seluruh variasi lebar yang ditinjau. Sementara itu, kinerja spintronik menunjukkan adanya kompromi antara rasio TMR dan efisiensi penyaringan spin. Seiring dengan bertambahnya lebar pita, rasio TMR meningkat, sedangkan efisiensi penyaringan spin cenderung menurun. Nilai tertinggi rasio TMR dan efisiensi penyaringan spin masing-masing mencapai 242% pada n = 12 dan sekitar 30% pada n = 6. Adanya kompromi antara kedua karakteristik tersebut menunjukkan bahwa MTJ berbasis pita nano grafena zig-zag/h-BN dengan variasi lebar memiliki potensi untuk dioptimalkan sesuai dengan kebutuhan aplikasi spintronik yang spesifik.
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Magnetic tunnel junctions (MTJs) are widely known for their tunneling magnetoresistance (TMR) effect, which offers promising potential for nextgeneration memory technologies. Quasi-one-dimensional materials-based MTJs are particularly attractive due to their reduced dimensions, which may enable higher device integration densities. In this study, zigzag graphene nanoribbons are employed as the ferromagnetic layers, while hexagonal boron nitride (h-BN) serves as the tunneling barrier. The nanoribbon width is varied by changing the number of zigzag chains, with n = 6, 8, 10, and 12. The electronic and spin-transport properties are investigated using first-principles calculations based on density functional theory combined with the nonequilibrium Green’s function formalism. The results show that the zigzag graphene nanoribbons retain their metallic character across all investigated ribbon widths. Meanwhile, the spintronic performance exhibits a tradeoff between the TMR ratio and spin-filtering efficiency. As the ribbon width increases, the TMR ratio enhances, whereas the spin-filtering efficiency tends to diminish. The maximum TMR ratio and spin-filtering efficiency reach 242% for n = 12 and approximately 30% for n = 6, respectively. This trade-off suggests that width-dependent zigzag graphene/h-BN nanoribbon-based MTJs can be optimized to meet the specific requirements of different spintronic applications.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	fungsi Green nonekuilibrium, persambungan terowongan magnetik, pita nano, rasio magnetoresistansi terowongan, teori fungsional densitas, density functional theory, nanoribbon, nonequilibrium Green’s function, spin-filtering efficiency, tunneling magnetoresistance ratio
Subjects:	Q Science > QC Physics
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Physics > 45201-(S1) Undergraduate Thesis
Depositing User:	Lailatul Fitri
Date Deposited:	30 Jul 2026 05:04
Last Modified:	30 Jul 2026 05:04
URI:	http://repository.its.ac.id/id/eprint/139923

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