@phdthesis{oai:mie-u.repo.nii.ac.jp:00014726,
 author = {Muhammad, Arifin},
 month = {Mar},
 note = {application/pdf, Optical sensors based on surface plasmon resonance (SPR) have advantages in measuring refractive index of material towards a development of highly sensitive biosensing sensors. Since the SPR-based sensors are limited in measuring chemical quantities such as concentrations of constituents, recent efforts have focused to utilize magneto-optical SPR (MOSPR), which combines magneto-optical Kerr effect (MOKE) to the SPR by using a hybrid magneto-plasmonic system consisting of ferromagnetic and noble metal thin films. With this background, the present dissertation devotes theoretical investigation of the electronic and optical properties of ferromagnetic/noble metal multilayers, based on first-principles calculations, and proposes a guideline for highly sensitive MOSPR sensors in term of material design.
The dissertation consists of six chapters. Chapter one states the basic concept of SPR and MOSPR, and presents purpose of study. Chapter two describes methodologies of calculations. First, method of electronic structure calculations based on density functional theory are presented where calculations are performed by using full-potential linearized augmented plane wave method. Second, the macroscopic and microscopic theories of the magneto-optical Kerr effect (MOKE) are presented. The optical conductivity tensors are calculated by applying the Kubo formula in the linear response theory and the reflectivities of multilayer systems are evaluated based on 4×4 transfer matrix method.
Chapter three provides systematically results of optical properties for transition metals, 3d (Fe, Ni, Co, Cu), 4d (Ru, Rh, Pd, Ag), and 5d (Os, Ir, Pt, Au) metals, by firstprinciples calculations. The transition metals, especially noble metals, are known to be desired candidates to plasmonic materials as used in sensing layers of the SPR applications. To clarify these optical characteristics, we calculated the optical conductivities and dielectric functions. Results for all systems can be reproduced to experimental trends. The edge position of the real part of diagonal optical conductivity of 1.7, 2.9, and 1.8 eV for Cu, Ag, and Au, respectively, can be confirmed by the band-by-band decomposition analysis proposed in the present study. We find that calculated SPR reflectivity curves of the noble metals in the Kretschmann configuration demonstrate sharp dips that correspond to small values of the imaginary parts of the dielectric functions.
In chapter four, the investigation is extended to apply ferromagnetic/noble metal multilayers, FexCux superlattices (SLs) withx = 1, 2, and 3. One of the main physical quantities in magnetoplasmonic is the optical loss caused by the dipole-interband transitions. From calculated electronic structures of FexCux SLs, we find that the interband transitions responsible in the optical losses that can be tuned through orbital hybridization by varying the thickness of the superlattices. In the visible range, FexCux SLs are found to have excellent magnetoplasmonic properties, indicated by negative real part of diagonal component of dielectric tensor and by non-zero off-diagonal component, which promise to martial candidates in the MOSPR applications. In addition, the electronic origin in the optical and magneto-optical anisotropies (OA and MOA) of the Fe1Cu1 SLs can be elucidated by the band-by-band decomposition analysis.
In chapter five, the MOSPR system with FexCux SLs as a magnetoplasmonic structure is proposed, where the TMOKE is employed in the Kretschmann configuration. The results show that a crossing position with respect to SPR angle between reflectivity curves for the positive and negative applied magnetization gives the strength of the TMOKE signal. Consequently, the maximum slopes of TMOKE signals results in 0.31,1.00, and 12.23 /degree for FexCux SLs with x = 1, 2, and 3, respectively. To concreting the MOSPR system by using FexCux SLs, when a small variation of the refractive index of a gelatin is introduced, the sensitivity in the MOSPR system is enhanced to 600.1 RIU-1 for Fe3Cu3 SL, which is two order of magnitude higher than that of the SPR system. Thus, the ferromagnetic/noble metal superlattice structure is promising choice to demonstrate high performance in the MOSPR applications.
Chapter six remarks conclusions and prospects of the present study., 本文/MIE UNIVERSITY Graduate School of Engineering Division of Materials Science, 82p},
 school = {三重大学},
 title = {First-Principles Study on Electronic and Optical Properties of Ferromagnetic/Noble Metal Multilayers and Its Application to Surface Plasmon Resonance},
 year = {2022}
}