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Longitudinal and Polar MOKE Magnetometry of
Magnetoresistive Cobalt
Thin Films Prepared by Thermal Evaporation
(Magnetometri
Longitudal dan Kutub MOKE Filem Nipis Kobalt Magnetorintangan yangdisediakan
Melalui Penyejatan Terma)
C. Sirisathitkul*
Magnet Laboratory, School of Science, Walailak
University, Nakhon Si Thammarat
80161 Thailand
Y. Pansong
Center of Scientific and Technological
Equipment, Walailak University
Nakhon Si Thammarat , 80161 Thailand
S. Rattanasuporn
Beamline Division, Synchrotron Light
Research Institute, Nakhon Ratchasima
30000 Thailand
Diserahkan: 3 Ogos 2011 / Diterima: 27 Oktober
2011
ABSTRACT
Cobalt films of
thickness 21, 29 and 68 nm were prepared by thermal evaporation with a
deposition rate around 0.3 nm/s. Their hysteresis loops from longitudinal and
polar magneto-optic Kerr effect (MOKE) magnetometry differed from typical
characteristics of uniaxial magnetic anisotropy but still indicated the
preference of in-plane anisotropy over perpendicular anisotropy. The
longitudinal hysteresis loop of the 68 nm-thick film was decidedly in a transcritical state signified by an enhanced coercive field.
Changing the angle (θ) between the 2500 Oe-magnetic field and the current
gave rise to the change in electrical resistance (Rθ) of 29 nm-thick film and the plot between Rθ and cos2θ could be
linearly fitted. The changes in resistance due to this anisotropic
magnetoresistance (AMR) effect ranged from -0.08 % (θ = 90º) to +0.04 %
(θ = 0º).
Keywords: Anisotropic magnetoresistance;
ferromagnetic thin film; hysteresis loop; magneto-optic Kerr effect; thermal
evaporation
ABSTRAK
Filem kobalt dengan ketebalan 21,29 dan 68 nm
telah disediakan melalui penyejatan terma dengan kadar pemendapan 0.3nm/s. Gelung histerisis daripada magnetometri longitudal dan
kesan magneto-optik Kerr adalah berbeza daripada ciri-ciri biasa anisotrop
magnet ekapaksi tetapi masih menunjukkan kecenderungnan kepada anisotrop
dalam-satah berbanding anisotropy serenjang. Gelung histerisis longitudal filem
dengan ketebalan 68 nm jelas dalam keadaan transkritikal dan ditandakan oleh medan paksaan yang meningkat. Mengubah sudut (θ) antara medan magnet 2500 Oe dan arus telah mengubah rintangan
elektrik (Rθ) filem dengan ketebalan 29 nm dan plot antara Rθ dan
cos2θ boleh disuaikan secara linear. Perubahan dalam rintangan disebabkan
oleh magnetorintangan tak isotropik (AMR) ini adalah daripada -0.08%
(θ=90o) ke 0.04% (θ= 0o).
Kata
kunci: Filem nipis feromagnet; gelung histerisis; kesan magneto-optik Kerr;
magnetorintangan anisotropik; penyejatanterma
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*Pengarang
untuk surat-menyurat; email: schitnar@wu.ac.th
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