Authors: Dr. James Michels, Dr. Sunil Labroo Department of Physics & Astronomy - SUNY Oneonta Magnetic Thin Film Analyses using an Optical Modulation System Objective • Assess Magnetic Thin Film Alloy Physical Properties • Provide Educational Research Project (Solid State Physics) Approach • Investigate Magnetic Hysteresis Effects • Two Experimental Methodologies: (1) Extraordinary Hall Effect Resistance Measurements (2) Magneto-Optic Kerr Effect (MOKE) Data Prior Extraordinary Hall Effect Data and Observations Prior Magneto – Optical Analyses 0.83 mT 2.0 mT 5.0 mT 8.1 mT 12.0 mT 0.00 0.50 1.00 1.50 2.00 -25 -20 -15 -10 -5 0 5 10 15 20 25 Hall Resistance (mΩ) B (mT) Hall Resistance vs B-Field 20% Cu in Ni Increasing B-field Decreasing B-field Increasing B-field Ordinary Hall Effect (metals and semi-conductors) x ( ) L d q E v B F Extraordinary Hall Effect (concentrations of magnetic materials) 0 0 e EH RB R M R t 0 H H RB V R I t 0 Current Ordinary Hall Coefficient I R 0 Extraordinary Hall Resistance Extraordinary Hall Coefficient Permeability of free space Magnetization EH e R R M Extraordinary Hall Effect Experimental Setup Sample Specifications • Film thicknesses of 2300-2500 Å • Current results for the 20% Ni in Cu setup • Other sample compositions: 1%, 5%, and 10%, Ni in Cu • Atomic fractions prepared using arc melting / thermal evaporation drift velocity d v B electric field vector E H V Lorentz Force t h I I B B y x z e F e v L F d v + + + + + + + + + + + + - - - - - - - - - - - - - H V - + Magnet Pole Magnet Pole Magnetic Field Vector Hall Voltage Hall Resistance Magneto - Optic Kerr Effect (MOKE) Apparatus H V H V Future Magneto-Optical Analyses • Kerr Cell Analyses • Birefringence Analyses • Structural Analysis – Magnetostriction (stress / strain) • Optical Communications • Spectral Analyses Laser Polarizer Polarizer (Analyzer) Electomagnet Poles Photoelastic Modulator (PEM) Light Detector Thin Film Light Chopper Lock-in Amplifier Oscilloscope Computer [1] [Tb 0.4 Fe 0.4 /Fe 0.5 Co 0.5 ] 3 multilayer film [2] Gd-Co film at several optical wavelengths References [1] Cerne, J., Magneto-Polarimetry Advanced Lab, Univ. Buffalo. [2] Sata, K., Jap. J. of Applied Physics, Vol. 20, No. 12, Dec. 1981 • CuNi alloy thin films • Concentrations of Ni in Cu (1%, 5%, 10%, 20%, 50%) Alternative Magneto-Optical Applications
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Authors: Dr. James Michels, Dr. Sunil Labroo Department of Physics & Astronomy - SUNY Oneonta
Magnetic Thin Film Analyses using an Optical Modulation System
Objective • Assess Magnetic Thin Film Alloy Physical Properties
• Provide Educational Research Project (Solid State Physics)
Approach • Investigate Magnetic Hysteresis Effects
• Two Experimental Methodologies:
(1) Extraordinary Hall Effect Resistance Measurements
(2) Magneto-Optic Kerr Effect (MOKE) Data
Prior Extraordinary Hall Effect Data and Observations
Prior Magneto – Optical Analyses
0.83 mT
2.0 mT
5.0 mT
8.1 mT
12.0 mT
0.00
0.50
1.00
1.50
2.00
-25 -20 -15 -10 -5 0 5 10 15 20 25
Hall R
esis
tan
ce
(m
Ω)
B (mT)
Hall Resistance vs B-Field 20% Cu in Ni
Increasing B-field
Decreasing B-field
Increasing B-field
Ordinary Hall Effect
(metals and semi-conductors)
x( )L d
q E v BF
Extraordinary Hall Effect
(concentrations of magnetic materials)
0 0e
EH
R B R MR
t
0H
H
R BVR
I t
0
Current
Ordinary Hall Coefficient
I
R
0
Extraordinary Hall Resistance
Extraordinary Hall Coefficient
Permeability of free space
Magnetization
EH
e
R
R
M
Extraordinary Hall Effect Experimental Setup
Sample Specifications
• Film thicknesses of 2300-2500 Å
• Current results for the 20% Ni in Cu setup • Other sample compositions: 1%, 5%, and 10%, Ni in Cu • Atomic fractions prepared using arc melting / thermal evaporation
drift velocitydv
B
electric field vectorE
HV
Lorentz Force
t
h
I I
B
B
y
x
z
eF
ev
LF
dv
+ + + + + + + + + + + +
- - - - - - - - - - - - -
HV- +
Magnet
Pole
Magnet Pole Magnetic
Field Vector
Hall
Voltage
Hall Resistance
Magneto - Optic Kerr Effect (MOKE) Apparatus
HV
HV
Future Magneto-Optical Analyses
• Kerr Cell Analyses
• Birefringence Analyses
• Structural Analysis – Magnetostriction (stress / strain)
• Optical Communications
• Spectral Analyses
Laser
Polarizer
Polarizer
(Analyzer)
Electomagnet
Poles
Photoelastic
Modulator (PEM)
Light
Detector Thin
Film
Light
Chopper
Lock-in
Amplifier Oscilloscope
Computer
[1] [Tb0.4Fe0.4/Fe0.5Co0.5]3
multilayer film [2] Gd-Co film at several
optical wavelengths
References
[1] Cerne, J., Magneto-Polarimetry Advanced Lab, Univ. Buffalo.
[2] Sata, K., Jap. J. of Applied Physics, Vol. 20, No. 12, Dec. 1981
• CuNi alloy thin films • Concentrations of Ni in Cu (1%, 5%, 10%, 20%, 50%)
Alternative Magneto-Optical Applications
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