The fate of quasiparticles in the superconducting state

Quasiparticle properties in the superconducting state are masked by the superfluid and are not directly accessible to infrared spectroscopy. We show how one can use a Kramers--Kronig transformation to separate the quasiparticle from superfluid response and extract intrinsic quasiparticle properties in the superconducting state. We also address the issue of a narrow quasiparticle peak observed in microwave measurements, and demonstrate how it can be combined with infrared measurements to obtain unified picture of electrodynamic properties of cuprate superconductors

The optimization of banking regulation intensity from the perspective of financial stability in banking sector: an empirical analysis

This paper investigates a multifactorial model, which allows defining an optimum level of banking regulation intensity based on the provision of a financial stability (at the macrolevel) and financial stability of banks (at the microlevel). An aggregated index of banking regulation intensity as well as an integrated index of financial stability of banks, which were the main factorial and resultative characteristic features during investigations, was formed for carrying-out of an empirical analysis. The optimum level of intensity of banking regulation has been suggested to define as the extremum of function of integrated index of financial stability of banks (determined by the method of the uniform optimality) on the relevant influencing factors (method of principal components)

An Infrared study of the Josephson vortex state in high-Tc cuprates

We report the results of the c-axis infrared spectroscopy of La_{2-x} Sr_x CuO_4 in high magnetic field oriented parallel to the CuO_2 planes. A significant suppression of the superfluid density with magnetic field rho_s(H) is observed for both underdoped (x=0.125) and overdoped (x=0.17) samples. We show that the existing theoretical models of the Josephson vortex state fail to consistently describe the observed effects and discuss possible reasons for the discrepancies

ScGAN: A Generative Adversarial Network to Predict Hypothetical Superconductors

Despite having been discovered more than three decades ago, High Temperature Superconductors (HTSs) lack both an explanation for their mechanisms and a systematic way to search for them. To aid this search, this project proposes ScGAN, a Generative Adversarial Network (GAN) to efficiently predict new superconductors. ScGAN was trained on compounds in OQMD and then transfer learned onto the SuperCon database or a subset of it. Once trained, the GAN was used to predict superconducting candidates, and approximately 70\% of them were determined to be superconducting by a classification model--a 23-fold increase in discovery rate compared to manual search methods. Furthermore, more than 99\% of predictions were novel materials, demonstrating that ScGAN was able to potentially predict completely new superconductors, including several promising HTS candidates. This project presents a novel, efficient way to search for new superconductors, which may be used in technological applications or provide insight into the unsolved problem of high temperature superconductivity

Heavy fermion fluid in high magnetic fields: an infrared study of CeRu4_4Sb12_{12}

We report a comprehensive infrared magneto-spectroscopy study of CeRu$_4$Sb$_{12}$ compound revealing quasiparticles with heavy effective mass m$^*$, with a detailed analysis of optical constants in fields up to 17 T. We find that the applied magnetic field strongly affects the low energy excitations in the system. In particular, the magnitude of m$^*$ $\simeq$ 70 m$_b$ (m$_b$ is the quasiparticle band mass) at 10 K is suppressed by as much as 25 % at 17 T. This effect is in quantitative agreement with the mean-field solution of the periodic Anderson model augmented with a Zeeman term

Electronic Structure and Charge Dynamics of Huesler Alloy Fe2TiSn Probed by Infrared and Optical Spectroscopy

We report on the electrodynamics of a Heusler alloy Fe2TiSn probed over four decades in energy: from the far infrared to the ultraviolet. Our results do not support the suggestion of Kondo-lattice behavior inferred from specific heat measurements. Instead, we find a conventional Drude-like response of free carriers, with two additional absorption bands centered at around 0.1 and 0.87 eV. The latter feature can be interpreted as excitations across a pseudogap, in accord with band structure calculations.Comment: 3 pages, 4 figure

Vector Control of Multiple Three-Phase Permanent Magnet Motor Drives

With the rapid development of power electronics, multiphase electrical solutions are becoming a competitive alternative to the conventional three-phase drives. Nowadays, the multiphase drives represent a robust and consolidated technology in both safety-critical and high-power applications. In addition, soon they will most likely be employed in the transportation electrification process. In this context, the multiple three-phase structures are undergoing an impressive development since they use the well consolidated three-phase technology reducing cost and design time. In this paper, a highperformance vector control for multiple three-phase permanent magnet motor drives is proposed. The developed solution employees a modular approach for the independent control of each three-phase unit. To show the feasibility of the developed control scheme, experimental results are provided for a ninephase permanent magnet machine employing a triple threephase configuration