Lee Young-Baek

We studied structures that describe the perfect-absorber effect by using different mechanisms. Firstly, we investigated the dependences of the reflectance and the absorbance of a metamaterial, as structure proposed by Landy <i>et al.</i> [Phys. Rev. Lett. <b>100</b>, 207402 (2008)] on gap ‘g’ of the structure at GHz frequencies. The value of the gap was obtained, which gives the maximum absorbance and the minimum reflectance. In addition, the change of geometry of the electric ring resonance as

The reflectance spectra of one-dimensional photonic crystals (PCs), consisting of alternating Ti2O3 and Al2O3 films with different repetition numbers, have been systematically simulated using the transfer-matrix method. The simulation was performed at oblique incidence and at normal incidence. The results are presented as a function of the repetition number, and a graphic method is employed to explain and understand the results in a visual way. At the designed wavelength,no omni-directional pho

The microstructures of ordered B2-phase and amorphous-like equiatomic CoTi alloy lms have been investigated by using X-ray absorption spectroscopy. Analysis of the extended X-ray absorption ne structure (EXAFS) data elucidates, at least in a local sense, that both Co and Ti atoms are arranged in an ordered cubic-B2 structure for the lm deposited on a heated substrate (730 K) while the lm deposited on a the substrate cooled down to 150 K is amorphous-like. The lm deposited at 150 K has the same m

(La0:7Sr0:3)0:5(Pr0:65Ca0:35)0:5MnO3 &macr;lms with dierent structural orders were prepared on LaAlO3 (001) substrates by \co-deposition" using the laser-ablation technique in order to investi-gate the eect of structural disorder on the magnetic properties. The &macr;lm deposited at 300 ±C was found to be a paramagnet with a narrow peak (&cent;T ' 10 K) at TG ' 45 K, which can be interpreted as a paramagnetic ! superparamagnetic transition. A short-term annealing at 750 ±C induced a high-textur

Apart from the specular magneto-optical Kerr effect (MOKE), the diffracted MOKE (D-MOKE) is another powerful tool to investigate the micromagnetic structures and the evolution of magnetic domains in gyrotropic gratings. It is vital to model D-MOKE completely and accurately. In this work, a rigorous coupled-wave approach is utilized, which is implemented as an Airy-like internal-reflection series, to simulate D-MOKE signals from one-dimensional gyrotropic gratings. The simulation was also done fo

Various physical properties for .lms of Heusler alloys, such as Ni2MnGe and Cu2MnAl, with dierent atomic orders were studied. The .lms were deposited on glass substrates at several sub- strate temperatures from 150 to 730 K. The structural characterization was performed by using X-ray diraction. A superconducting-quantum-interference-device magnetometer was employed to measure the temperature dependence of the spin properties. The photonic and the spin-photonic properties were also investigated.

We investigated systematicaly the electromagnetic behavior of different magnetic metamaterials, from the split-ring resonator to the cut-wire pair, for providing a negative magnetic permeability. The combination of a cut-wire pair and a continuous wire was also studied experimentaly. We found that the combined structure exhibited both left- and right-handed transmision bands. Until the width of the cut-wire pair was increased to merge with the adjacent continuous wire to form the so-caled fishne

In this paper, we report the synthesis and the magnetic properties of Mn-doped ZnO (ZnMnO) nanorods. The ZnMnO nanorods were fabricated by using a two-step method. The properties of the prepared nanorods were investigated by using scanning electron microscopy, X-ray diffraction, Rutherford backscatter spectroscopy, and a superconducting quantum interference device magnetometer. The X-ray diffraction analysis revealed that Mn was incorporated well into the wurtzite ZnO without forming any seconda

We systematically study the transmission properties of metallic cut-wire pair (CWP) structure,using the transfer-matrix method and the commercial code, CST Microwave Studio. The electric and the magnetic resonances of CWP structure are demonstrated by the effective medium anal-yses. The corresponding effective permittivity and permeability are calculated from the complex scattering parameters by using the standard retrieval procedure. In addition, the dependence of the transmission properties an

One-dimensional gyrotropic gratings can be fabricated by using all kinds of nano-fabrication techniques. Such laterally patterned magnetic nanostructures become more attractive because of their potential applications to magnetic and magneto-optical (MO) information storage media, light waveguides, filters, new metamaterials, etc. A significant difference in the MO response between specular and non-specular spots was noticed, which is mainly attributed to the structure of gyrotropic gratings. In

We measured the transmission spectra of left-handed materials (LHMs) by using a cut-wire pair, instead of split-ring resonator to effectively produce a negative magnetic permeability. To achieve LH properties, cut-wire pairs were combined with continuous wires. These structures were designed and fabricated and their transmission spectra were measured in the microwave frequency region. It was found that the combined structures exhibited a pass band within the stop band of the cut-wire pair and co

The transmission properties of one-dimensional (1-D) symmetric spin photonic crystals (SPCs), consisting of dielectric SiO₂ and magnetic bismuth-substituted YIG multilayers, were investigated. The perfectly periodic structures yield the same transmittance spectra, regardless of the order of the layers. The order of the layers in the SPCs, including defect layers, influences the transfer characteristics. More magnetic defect layers bring about a broader width of photonic bandgap and a larger tran

Cobalt anti-dot square-lattice arrays of different periodicities were fabricated using the photolithography and wet-etching process. The dimensions of these 2-dimensional spin photonic crystals were checked by using scanning electron microscopy and atomic force microscopy whereas the magnetic properties were studied using the magneto-optical Kerr effect (MOKE) and magnetic force microscopy (MFM). The in-plane azimuthal MOKE measurements showed uniaxial two-fold anisotropy with the hard and the e

The magnetic properties of a magnetic grating produced by using femtosecond-laser-induced selective-area crystallization of amorphous Ni2MnGa lms were elucidated. The amorphous Ni2MnGa films were fabricated on a glass substrate by dc magnetron sputtering. A periodic structure was obtained by using two-beam interference of the laser pulses. The atomic-force-microscopy image showed regularly-spaced alternating lines with a periodicity of 2 m. The corresponding magnetic-force-microscopy image also

Spin-photonic crystals (SPCs) are very promising for applications in modern photonics because they possess an additional degree of freedom. The SPCs can be prepared as periodic one-, two-, and three-dimensional structures composed of, at least, two different magnetic and nonmagnetic, or magnetic and magnetic materials with different refractive indices. The linear SP properties of one-dimensional SPCs with three-defect asymmetric structures were studied. The requirements of a Kerr rotation of abo