| |
 |
UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS Guest
2024-11-23 18:00 |
 |
|
|
|
Conference: Bucharest University Faculty of Physics 2022 Meeting
Section: Solid State Physics and Materials Science, Optics, Spectroscopy, Plasma and Lasers
Title:
Optical properties of the oxidized Terfenol-D thin film obtained by pulsed laser deposition
Authors:
Ruxanda MIREANU(1), Valentin ION(2), Ovidiu TOMA(1)
Affiliation:
1) University of Bucharest, Faculty of Physics, POBox MG-11, Magurele-Bucharest, Magurele, Ilfov, Romania
2) National Institute for Laser, Plasma and Radiation Physics
Atomistilor Str., No. 409, PO Box MG-16, 077125, Magurele, Ilfov, Romania
E-mail
ruxandamireanu@gmail.com, valentin.ion@inflpr.ro, thtoma72@yahoo.com
Keywords:
Terfenol-D, Pulsed Laser Deposition, metallic alloy, oxidized thin films, Spectroscopic Ellipsometry, AFM, SEM, EDX, magnetostriction, Lorentz model, Effective medium approximation (EMA) model.
Abstract:
The main goal of this thesis consists in the characterization of Terfenol-D thin films, through spectroscopic ellipsometry measurements. For this research activity we have realized Terfenol-D (TbxDy1-xFe2) thin films of two different concentrations: Tb0.3Dy0.7Fe2 and Tb0.4Dy0.6Fe2, knowing that the magnetostrictive property of Terfenol-D changes with the variation in the Tb and Dy ratio.
The analyzed probes were deposited on Si (100), Si (111) and Pt/Si substrates, at room temperature as well as temperatures of 300oC, 500oC, 600oC. In the PLD configuration we have used the solid body Nd:YAG laser as a light source, characterized by a wavelength of 266 nm and a pulse repetition rate of 10 Hz. Other important deposition parameters were the heating rate of 50oC, cooling temperature of 10oC per minute, distance between target and film of 4 cm and the number of pulses of 36000 per hour. Moreover, the deposition process took place in vacuum conditions, using a laser fluence of 1.2 J/cm2.
Optical constant’s dispersion was analyzed through the sensitive technique of spectroscopic ellipsometry (SE), which uses the elliptically polarized light reflected by a sample to fit the (ψ, Δ) parameters. The product of Δ and tan(ψ) gives the ratio of Fresnel reflection coefficients for s- and p-polarized light. The basic mechanism of SE consists in the comparison of the experimental data with a generated model constructed using proper dispersion equations. In this paper we have used a combination of the Lorentz oscillator model and the effective medium approximation (EMA), in order to fit the Terfenol-D films which indicated the presence of iron oxides on their surface, due to deposition conditions.
Besides the SE analysis, different probes were characterized through AFM, SEM, EDX and resistivity measurements.
|
|
|
|