Critical magnetic elds in superconducting systems with semi-metallic bands

In this work, we study the Zeeman splitting effects in the parallel magnetic field versus temperature phase diagram of two-dimensional superconductors with one graphene-like band and the orbital effects of perpendicular magnetic fields in isotropic two-dimensional semi-metallic superconductors. We show that when parallel magnetic fields are applied to graphene and as the intraband interaction decreases to a critical value, the width of the metastability region present in the phase diagram decreases, vanishing completely at that critical value. In the case of two-band superconductors with one graphene-like band, a new critical interaction, associated primarily with the graphene-like band, is required in order for a second metastability region to be present in the phase diagram. For intermediate values of this interaction, a low-temperature first-order transition line bifurcates at an intermediate temperature into a first-order transition between superconducting phases and a second-order transition line between the normal and the superconducting states. In our study on the upper critical fields in generic semi-metallic superconductors, we find that the pair propagator decays faster than that of a superconductor with a metallic band. As result, the zero field band gap equation does not have solution for weak intraband interactions, meaning that there is a critical intraband interaction value in order for a superconducting phase to be present in semi-metallic superconductors. Finally, we show that the out-of-plane critical magnetic field versus temperature phase diagram displays a positive curvature, contrasting with the parabolic-like behaviour typical of metallic superconductors.

O produto à medida do cliente na Miranda & Irmão, LDA

Este relatório tem como objetivo descrever todas as atividades desenvolvidas durante o período de estágio na Miranda & Irmão, Lda, e apresentar um estudo detalhado das estratégias implementadas para a retenção de clientes, contribuindo, assim, para a criação de valor através do Marketing Relacional. O Marketing Relacional tem vindo a ganhar destaque na criação de estratégias de negócio, contribuindo para a fomentação de relações estáveis e duradouras entre as empresas e os seus clientes. Inserido nesta estratégia, a “Infinium” é um produto premium criado para alavancar a marca “Miranda” com recurso a produtos tecnologicamente transcendentes e para dar resposta a um novo nicho de mercado.