Analisa Magnetoresistance Berbasis Lapisan Tipis Giant Magnetoresistance (GMR) Pada Nanopartikel Cobalt Ferrite (CoFe2O4) Dilapisi Polyethylen Glicol (PEG)

NOVI SUSANTI, Dr. Edi Suharyadi, M.Eng

2015 | Tesis | S2 Ilmu Fisika

Telah dilakukan pengukuran magnetoresistance pada lapisan tipis spin valve GMR yang memiliki struktur CoFeB/Cu/CoFe/MnIr dengan memvariasikan ketebalan lapisan barrier Cu (2,2 dan 2,8 nm) dan free layer CoFeB (7 dan 10 nm) menggunakan System Four Point Probe Method (SFPPM) pada medan eksternal 0-600 gauss. Dihasilkan perubahan range resistansi (69,29-71,74) Ohm untuk Cu 2,2 nm dan (38,5-40,47) Ohm untuk ketebalan Cu 2,8 nm. Pada variasi ketebalan CoFeB dihasilkan perubahan range resistansi untuk ketebalan 7 nm dan 10 nm masing masing adalah (38,74-41,11) Ohm dan (69,29-71,74) Ohm. Selanjutnya lapisan tipis digunakan sebagai sensor magnetik untuk mendeteksi kehadiran nanopartikel CoFe2O4, CoFe2O4 yang dimodifikasi PEG dan CoFe2O4 termodifikasi PEG yang telah mengikat biomolekul formalin. Terjadi pergeseran nilai resistansi ketika lapisan tipis dilapisi nanopartikel magnetik tersebut. hal ini menunjukkan bahwa lapisan tipis GMR mampu mendeteksi prilaku spin pada nanopartikel magnetik CoFe2O4.

Magnetoresistance measurements were carried out in a thin film of the spin valve GMR structure CoFeB/Cu/CoFe/MnIr by varying the thickness of the barrier layer of Cu (2,2 and 2,8 nm) and CoFeB free layer (7 and 10 nm) using Four Point Probe Method (SFPPM)in the external field 0-600 gauss. it was found that the changes in the resistance range were (69,29-71,74) Ohm for Cu 2,2 nm and (38,5-40,47) Ohm for Cu 2,8 nm. In variations of CoFeB thickness, the changes in the resistnce range for the thickness of 7 nm and 10 nm were (38,74-41,11) Ohm and (69,29-71,74) Ohmrespectively. furthermore, a thin layer is used as amagnetic sensor to detect the presence of CoFe2O4 nanoparticles, PEG coated CoFe2O4 and CoFe2O4 modified by PEG that was bonded with formalin biomolecules. A shift in resistance value occurs when a thin layer of the coated magnetic nanoparticles. This suggests that the thin layer of the GMR is able to detect the behavior of magnetic spins of CoFe2O4 magnetic nanoparticles.

Kata Kunci : Giant magnetoresistance,lapisan tipis, nanopartikel CoFe2O4, Polyethylen glicol/ Giant magnetoresistance,thin film, CoFe2O4 nanoparticles, polyethylen glicol