Kamsul Abraha

Theory of far infrared properties of magnetic surfaces, films and superlattices

Abstract Many magnetic materials, particularly antiferromagnets and ferrimagnets, have resonance frequencies in the far infrared, say between 10 and 100 cm−1. The first experimental studies of these were by absorption spectroscopy but in the last 15 years attention has shifted to a more ‘optical’ point of view in the study of reflection and transmission. Experimental techniques that are now available should lead to a rapid expansion of such studies. This expansion is likely to include the application of far-infrared spectroscopy to characterisation, that is, the determination of the basic magnetic parameters of samples. Particular interest will attach to thin films and superlattices. We review the theoretical framework necessary for the interpretation of such experiments. The first part of the review is devoted to existing studies, particularly resonance, reflectivity and transmissivity studies of antiferromagnets and ferrimagnets. We include a brief section on growth of thin films and superlattices. The underlying quantity is the dynamic permeability tensor μ(ω). In the second part we discuss derivations of μ(ω) for various magnetic materials and then give an account of derivations of reflectivity from μ(ω). Experimental data often exhibit the property of non-reciprocity, that is, the reflectivity, for example, changes when the static magnetic field is reversed. In some cases non-reciprocity occurs only when the sample is dissipative while in others it is intrinsic. We pay attention to non-reciprocity throughout the review and in a final section we review the results of discussions based on thermodynamics.

Defect-induced large spin-orbit splitting in monolayer PtSe2

The effect of spin-orbit coupling on the electronic properties of monolayer (ML)

Polarity tuning of spin-orbit-induced spin splitting in two-dimensional transition metal dichalcogenides

{\mathrm{PtSe}}_{2}

Influence of stabilizing agent and synthesis temperature on the optical properties of silver nanoparticles as active materials in surface plasmon resonance (SPR) biosensor

is dictated by the presence of the crystal inversion symmetry to exhibit a spin-polarized band without the characteristic of spin splitting. Through fully relativistic density-functional theory calculations, we show that large spin-orbit splitting can be induced by introducing point defects. We calculate the stability of native point defects such as a Se vacancy (

Electrical characteristic of spin coated Fe-Porphyrin on Cu substrates

{\mathrm{V}}_{\text{Se}}

The use of Fe3O4 magnetic nanoparticles as the active layer to detect plant’s DNA with surface plasmon resonance (SPR) based biosensor

), a Se interstitial (

Utilization of natural porphyrin thin films as a photosensitizer for photodetectors

{\mathrm{Se}}_{i}

Commensurate effects in the square superconductor with a regular holes array

), a Pt vacancy (

Computational Study of Sensitivity Enhancement in Surface Plasmon Resonance (SPR) Biosensors by Using the Inclusion of the Core-Shell for Biomaterial Sample Detection

{\mathrm{V}}_{\text{Pt}}

Chirality Analysis on a Square Chiral Metamaterial

), and a Pt interstitial (