Electronic structure and the Fermi surface of ThRhIn5_5 in comparison with uranium and transuranium compounds

By using a relativistic linear augmented-plane-wave method, we clarify energy band structure and the Fermi surfaces of recently synthesized thorium compound ThRhIn$_5$. We find several cylindrical Fermi surface sheets, which are similar to those of CeTIn$_5$ (T=Ir and Co), PuTGa$_5$ (T=Co and Rh), and AmCoGa$_5$. We discuss such similarity among the compounds including rare-earth or actinide ions with different $f$ electron numbers.Comment: 2 pages, 2 figure, Proceedings of SCES'05 (July 26-30, 2005, Vienna

Electronic structure and the Fermi surface of UTGa_{5} (T=Fe, Co, Rh)

The relativistic energy-band calculations have been carried out for UFeGa_{5}, UCoGa_{5} and URhGa_{5} under the assumption that 5f-electrons are itinerant. A hybridization between the U 5f state and Ga 4p state occurs in the vicinity of the Fermi level. The Fermi surface of UCoGa_{5} is quite similar to that of URhGa_{5}, which are all small in size and closed in topology. UFeGa_{5} has the quasi-two-dimensional Fermi surface which looks like a lattice structure.Comment: 2 pages, 3 figures, LT23auth.cls, elsart.cls. submitted to conference LT2

Spin Fluctuation Induced Superconductivity Controlled by Orbital Fluctuation

A microscopic Hamiltonian reflecting the correct symmetry of $f$-orbitals is proposed to discuss superconductivity in heavy fermion systems. In the orbitally degenerate region in which not only spin fluctuations but also orbital fluctuations develop considerably, cancellation between spin and orbital fluctuations destabilizes $d_{x^{2}-y^{2}}$-wave superconductivity. Entering the non-degenerate region by increasing the crystalline electric field, $d_{x^{2}-y^{2}}$-wave superconductivity mediated by antiferromagnetic spin fluctuations emerges out of the suppression of orbital fluctuations. We argue that the present scenario can be applied to recently discovered superconductors CeTIn$_{5}$ (T=Ir, Rh, and Co).Comment: 4 pages, 3 figure

Estudio de mejora para la reducción del gasto de destrucción en una empresa del sector cosmético

En un contexto mundial para la sostenibilidad en los negocios, el tratamiento de desechos a través de un proceso de eliminación responsable con el medio ambiente ha pasado a ser uno de los desarrollos claves para las empresas. La empresa estudiada en este trabajo, líder en el sector cosmético, ha tomado la decisión de lanzar un proyecto con el propósito de reducir el impacto económico que ocasiona la destrucción de mercadería y al mismo tiempo minimizar el impacto ambiental que sus destrucciones generan. Desafortunadamente, Perú es un país donde el manejo de residuos aún se encuentra en una etapa incipiente comparándolo con el desarrollo de Europa. Esto se ve claramente en la preferencia de las empresas por mandar sus residuos a rellenos sanitarios, donde la mercadería es compactada y posteriormente depositada en el suelo. Existe una oferta muy pequeña de proveedores que realicen un proceso de disposición de desechos responsable con el medio ambiente, como es el de incineración y tratamiento de gases originados por su combustión, pero este proceso tiene una gran desventaja económica debido a que sus costos pueden ascender a cuatro veces más que el proceso tradicional. Por este motivo, la mayoría de las empresas peruanas no optan por este método. Considerando esta desventaja, el desarrollo de la estrategia para la reducción de gastos de destrucción, se basa en las siguientes etapas: prevenir, reusar, reciclar y tomar solo como última opción, la destrucción de desechos. La primera labor a realizar es la de cuantificar e identificar las causas origen de los desechos y generar planes para cada etapa planteada. La estrategia expone construir un marco estratégico donde se definan los pasos claves, los equipos de trabajo y de indicadores de gestión que apoyen a revisar los avances de cada plan. Durante el transcurso del 2018, distintos acontecimientos obligaron a la empresa a realizar un ajuste del proyecto de implementación y para septiembre del mismo año se replanteó el tiempo del proyecto llevándolo de 3 años a 5 años, para lograr el objetivo de 0,5% de gastos de destrucción.The global context for business sustainability has become one of the key developments for companies around the world. The waste treatment has to be done though a responsible process which minimizes the impact to the environment. The company selected in this text, which is one the leaders in the cosmetic sector, has made the decision to launch a project with the purpose of reducing the economic impact caused by its product’s scrapping and at the same time, minimizing its environmental impact. Unfortunately, Peru is a country where the waste management is still on an incipient staged, compared to the development that has Europe. This is clearly seen, in the several companies that has the preference to send their disposals to landfills, where the products are compacted and subsequently deposited on the ground. There is a very small range of suppliers who make a responsible waste disposal to the environment, such as incineration and then the combustion’s gas treatment, but this process has a big economic disadvantage, because the costs can be four times more expensive than the traditional process. For this reason, the majority of the peruvian companies do not choose this method. Considering this disadvantage, the development of the strategy to reduce the scrapping cost is based on the following stages: prevent, reuse, recycle and the waste scrapping as a last resource. The first step is to quantify and identify the waste’s root causes and generate plans for each stage proposed. The strategy exposes the construction of a framework that will define the key steps, the responsible work teams, and the keys performances indicators to support the progress of each plan. During the curse of 2018, different events forced the company to make an adjustment of the project and by september of the same year, the project time line was changed from 3 years to 5 years in order to achieve the objective of 0,5% of scrapping cost

Strong-coupling theory of superconductivity in a degenerate Hubbard model

In order to discuss superconductivity in orbital degenerate systems, a microscopic Hamiltonian is introduced. Based on the degenerate model, a strong-coupling theory of superconductivity is developed within the fluctuation exchange (FLEX) approximation where spin and orbital fluctuations, spectra of electron, and superconducting gap function are self-consistently determined. Applying the FLEX approximation to the orbital degenerate model, it is shown that the $d_{x^2-y^2}$-wave superconducting phase is induced by increasing the orbital splitting energy which leads to the development and suppression of the spin and orbital fluctuations, respectively. It is proposed that the orbital splitting energy is a controlling parameter changing from the paramagnetic to the antiferromagnetic phase with the $d_{x^2-y^2}$-wave superconducting phase in between.Comment: 4 figures, submitted to PR

Electronic Structure and Fermiology of PuCoGa5_5

By using a relativistic linear augmented-plane-wave method, we clarify energy band structures and Fermi surfaces of recently discovered plutonium-based superconductor PuCoGa$_5$. We find several cylindrical sheets of Fermi surfaces with large volume, very similar to CeMIn$_5$ (M=Ir and Co) isostructural with PuCoGa$_5$, in spite of different $f$-electron numbers between Ce$^{3+}$ and Pu$^{3+}$ ions. The similarity is understood by a concept of electron-hole conversion in a tight binding model constructed based on the $j$-$j$ coupling scheme. Based on the present results, we provide a possible scenario to explain why a transition temperature is so high as 18.5K in PuCoGa$_5$.Comment: 4 pages, Revtex, with 4 figures embedded in the text. Submitted to Phys. Rev. Let