SIUC Physics Seminar
School of Physics and Applied Physics, Southern Illinois University--Carbondale
2025 November 21 Friday 3:00 PM:
Physics Seminar in Neckers 440
Title: Measurement of Kerr rotation and Fresnel reflection coefficients using a rotating polarizer method
Speaker: Shusmita Podder Pooza
Affiliation: Southern Illinois University--Carbondale
Abstract:
The magneto-optical Kerr effect (MOKE) occurs when polarized light reflects from
a magnetized surface, causing a small change in the polarization angle and state.
Measurement of the complex Kerr angle is well established and typically performed
close to the null configuration in a polarizer-analyzer geometry\(^{[1]}\).
In this work, we developed a method to measure the Kerr rotation
and Fresnel reflection coefficients by varying the incident beam polarization angle
and measuring the s- and p-polarized reflected light intensities using a Wollaston prism.
We will present a Jones Matrix analysis of our setup as a function of the
incident polarization and fit the equations to our experimental MOKE hysteresis loop data.
In addition to being a multi-point analysis method, this process allows us to measure
the Kerr rotation and the Fresnel coefficients, including the magneto-optic reflection terms.
Using cobalt thin film as an example, we estimated the Kerr rotation of
1 mrad, |rp/rs|= 0.77, and |rps/rs|=0.12 at a 45-degree angle of incidence.
Such values will be compared with the literature and presented.
References:
D. H. Suzuki and G. S. D. Beach,
Measurement of Kerr rotation and ellipticity in magnetic thin films by MOKE magnetometry
J. App. Phys. 135 (2024) 063901, doi: 10.1063/5.0185341.
Biography:
I am Shusmita Podder Pooza, a dedicated physics researcher and educator.
I completed my Bachelor of Science and Master of Science in Physics from the University of Dhaka,
one of the most prestigious institutions in Bangladesh. Currently,
I am pursuing my second master's degree in physics at Southern Illinois University, Carbondale,
where I joined in January 2024.
My research focuses on experimental condensed matter physics,
particularly the magneto-optical Kerr effect (MOKE). I study and quantify
the magnetic properties of novel magnetic thin films,
used to study the magnetization pattern in thin films.
This technique can characterize new materials used in memory storage devices.
Alongside my research, I work as a Graduate Teaching Assistant,
conducting lab sessions and assisting students in hands-on experimental learning.
My passion for physics extends beyond the classroom,
and I genuinely enjoy exploring new experiments and engaging with students
during my TA responsibilities.
Outside of academics, I have a deep fascination with the sky--I love observing its color changes,
spotting planets with the naked eye, and witnessing breathtaking sunrises and sunsets.
I also have a strong passion for tracking weather patterns and exploring nature's wonders.
My fascination with the beauty and dynamics of the sky is an endless source of inspiration for me.
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by K V Shajesh
(kvshajesh@gmail.com).