Yu. V. Kudryavtsev

Bio: Yu. V. Kudryavtsev is an academic researcher from National Academy of Sciences of Ukraine. The author has contributed to research in topics: Amorphous solid & Alloy. The author has an hindex of 14, co-authored 81 publications receiving 730 citations.

Effect of disorder on various physical properties of Co 2 CrAl Heusler alloy films: Experiment and theory

Abstract: We have investigated the effects of atomic disorder on the electronic structure and some physical properties of ${\text{Co}}_{2}\text{CrAl}$ Heusler alloy (HA) films. Flash evaporation onto glass substrates at different temperatures (from 150 to 750 K) and postannealing at various temperatures were employed to manipulate the structural order in ${\text{Co}}_{2}\text{CrAl}$ HA films. The $L{2}_{1}$-ordered ${\text{Co}}_{2}\text{CrAl}$ HA films exhibit the magnetic, the transport, and the optical properties close to those of the bulk ordered sample. Increase in the structural disorder ($L{2}_{1}\ensuremath{\rightarrow}B2\ensuremath{\rightarrow}A2\ensuremath{\rightarrow}\text{amorphous}$ state) causes the reduction in the saturation magnetization and the Curie temperature $({T}_{C})$ down to the paramagnetic state for amorphous films. The recrystallization of amorphous ${\text{Co}}_{2}\text{CrAl}$ HA films is accompanied by an increase in resistivity by about 10%, which is interpreted to be related to the energy gap formation at the Fermi level for the minority bands in the $L{2}_{1}/B2$-ordered state of ${\text{Co}}_{2}\text{CrAl}$ HA. The energy-band structures of $L{2}_{1}$-ordered ${\text{Co}}_{2}\text{CrAl}$ HA have been calculated by using an all-electron full-potential linearized-augmented-plane-wave method. The optical and the magneto-optical properties of $L{2}_{1}$-ordered ${\text{Co}}_{2}\text{CrAl}$ HA have been experimentally investigated and explained in terms of the band structures. It was experimentally shown that the optical properties of crystalline $L{2}_{1}$ (or $B2$)-type ordered alloy at a temperature much higher than ${T}_{C}$ do not significantly change. Structural disorder in ${\text{Co}}_{2}\text{CrAl}$ HA from the crystalline to the amorphous state also does not radically alter the states responsible for the interband-absorption-peak formation.

The optical properties of

Abstract: The optical properties of have been deduced using spectrophotometry and ellipsometry and calculated within the extended linear augmented plane wave framework in the energy range 0 - 6 eV. Good agreement amongst all approaches is obtained up to about 2 eV, beyond which there is some divergence between theory and experiment where, for reasons discussed, the theory needs further refinement.

Magneto-optical and optical properties of Fe-rich Au-Fe alloy films near the fcc-bcc structural transformation region

Abstract: A set of Au 1 - x Fe x alloy films with 0 080 The equatorial-Kerr-effect (EKE) spectra for the Au 1 - x Fe x alloy films with bcc and fcc types of structure show noticeably different spectral shapes and magnitudes from each other Moreover, the EKE value in the UV region for the Fe-rich Au 1 - x Fe x alloy films exceeds that for the pure Fe film The observed blueshift and redshift of the low- and high-energy peaks, respectively, of the Fe-rich Au 1 - x Fe x alloy films with respect to pure Fe are caused by differences in the optical constants between alloy and Fe films, which cannot explain, on the other hand, the enhancement of EKE value for the bcc Au 1 - x Fe x alloys The optical-conductivity (OC) spectra for the Au 1 - x Fe x alloy films with bcc type of structure are characterized by an intense interband absorption peak at 20 eV which is completely absent in the OC spectra of the Au 1 - x Fe x alloy films with fcc type of structure The spectra of absorptive part of the off-diagonal components of dielectric function for the investigated Au 1 - x Fe x alloy and Fe films exhibit a double-peak structure; a peak near 18 eV (which does not depend on the composition or the structural state of alloy) and a high-energy peak The latter is located at 33 eV for the Au 1 - x Fe x alloy films with fcc type of structure and at 40-42 eV for the alloys with bcc structure as well as for the Fe film

Surface plasmon resonance in gold nanoparticles: a review.

Abstract: In the last two decades, plasmon resonance in gold nanoparticles (Au NPs) has been the subject of intense research efforts. Plasmon physics is intriguing and its precise modelling proved to be challenging. In fact, plasmons are highly responsive to a multitude of factors, either intrinsic to the Au NPs or from the environment, and recently the need emerged for the correction of standard electromagnetic approaches with quantum effects. Applications related to plasmon absorption and scattering in Au NPs are impressively numerous, ranging from sensing to photothermal effects to cell imaging. Also, plasmon-enhanced phenomena are highly interesting for multiple purposes, including, for instance, Raman spectroscopy of nearby analytes, catalysis, or sunlight energy conversion. In addition, plasmon excitation is involved in a series of advanced physical processes such as non-linear optics, optical trapping, magneto-plasmonics, and optical activity. Here, we provide the general overview of the field and the background for appropriate modelling of the physical phenomena. Then, we report on the current state of the art and most recent applications of plasmon resonance in Au NPs.

Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection

Abstract: Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection

High temperature shape memory alloys

Abstract: Shape memory alloys (SMAs) with high transformation temperatures can enable simplifications and improvements in operating efficiency of many mechanical components designed to operate at tem...

A review of the optical properties of alloys and intermetallics for plasmonics

Abstract: Alternative materials are required to enhance the efficacy of plasmonic devices. We discuss the optical properties of a number of alloys, doped metals, intermetallics, silicides, metallic glasses and high pressure materials. We conclude that due to the probability of low frequency interband transitions, materials with partially occupied d states perform poorly as plasmonic materials, ruling out many alloys, intermetallics and silicides as viable. The increased probability of electron-electron and electron-phonon scattering rules out many doped and glassy metals.

Accuracy of ab initio methods in predicting the crystal structures of metals: A review of 80 binary alloys

Abstract: Predicting and characterizing the crystal structure of materials is a key problem in materials research and development. We report the results of ab initio LDA/GGA computations for the following systems: AgAu, AgCd, AgMg, AgMo∗, AgNa, AgNb∗, AgPd, AgRh∗, AgRu∗, AgTc∗, AgTi, AgY, AgZr, AlSc, AuCd, AuMo∗, AuNb, AuPd, AuPt∗, AuRh∗, AuRu∗, AuSc, AuTc∗, AuTi, AuY, AuZr, CdMo∗, CdNb∗, CdPd, CdPt, CdRh, CdRu∗, CdTc∗, CdTi, CdY, CdZr, CrMg∗, MoNb, MoPd, MoPt, MoRh, MoRu, MoTc∗, MoTi, MoY ∗, MoZr, NbPd, NbPt, NbRh, NbRu, NbTc, NbY ∗, NbZr∗, PdPt, PdRh∗, PdRu∗, PdTc, PdTi, PdY, PdZr, PtRh, PtRu, PtY, PtTc, PtTi, PtZr, RhRu, RhTc, RhTi, RhY, RhZr, RuTi, RuTc, RuY, RuZr, TcTi, TcY, TcZr, TiZr∗, Y Zr∗ (∗= systems in which the ab initio method predicts that no compounds are stable). A detailed comparison to experimental data confirms the high accuracy with which ab initio methods can predict ground states.