Doutorado em Física
URI Permanente para esta coleção
Nível: Doutorado
Ano de início: 2003
Conceito atual na CAPES: 4
Ato normativo: Parecer CES/CNE nº 487/2018, homologado pela Port. MEC 609, publicado no DOU em 18/03/2019.
Periodicidade de seleção: Semestral
Área(s) de concentração: Física
Url do curso: https://fisica.ufes.br/pt-br/pos-graduacao/PPGFis/detalhes-do-curso?id=1509
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Navegando Doutorado em Física por Autor "Amorim, Rodrigo Garcia"
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- ItemDetecção e identificação elétrica dos nucleotídeos do DNA via nanoporo híbrido de grafeno e nitreto de boro hexagonal: um estudo teórico.(Universidade Federal do Espírito Santo, 2017-09-15) Souza, Fábio Arthur Leão de; Scopel, Wanderlã Luis; Canal Neto, Antônio; Freitas, Jair Carlos Checon de; Campos, César Turczyn; Amorim, Rodrigo Garcia; Silva, Edison Zacarias daIn this thesis work, a novel architecture of solid-state nanopore in a hybrid two-dimensional (2D) material for detection and identification of biomolecules is proposed. The system is composed of a zigzag graphene nanoroad embedded in hexagonal boron nitride (h-BN). A theoretical study based on ab-initio calculations was carried out to assess its energetic stability, structural, electronic and transport properties. Our results indicate the capability of controlling by gate voltage the current pathways through the conducting graphene strip. Then, motivated by the recently developed electrochemical reaction (ECR) technique for fabricating nanopores in a highly controlled manner in 2D materials, and aiming to evaluate the possibility of drilling pores in the hybrid material, vacancy defect formation energies of carbon, boron and nitrogen were evaluated throughout different regions of the system. As a result, our findings suggest that it would be possible to drill a pore in graphene nanoroad from a carbon vacancy in the graphene/h-BN interface, keeping just a carbon chain between the pore and h-BN domain in the opposite interface. Accordingly, a pore of approximately 12.5Å in diameter with aforementioned characteristics was built. Therefore, to develop and assess the feasibility of such proposed device to act as nanosensor, a combination of density functional theory with non-equilibrium Green’s function methods were employed. Hence, investigations on how each nucleotide that forms DNA should modulate the local current at the nanopore device were performed, where four nucleotides were tested: deoxyadenosine monophosphate (dAMP), deoxyguanosine monophosphate (dGMP), deoxycytidine monophosphate (dCMP), and deoxythymidine monophosphate (dTMP). Analyses of the pore+nucleotide zero-bias transmission functions have revealed that it should be in principle possible to distinguish between all four nucleotides inside the nanopore setup, which should occur in practice by their sensitivity fingerprints in real-time conductance measurements. Furthermore, it was demonstrated that the mechanism of detection of the referred hypothetical sensor is governed by modulation of the conductance of the carbon chain running along the graphene/h-BN interface due to local dipole moments of the target molecule.
- ItemElectronic Properties of Single-layer In2 Se3: from Photocatalysis to Non-trivial Band Topology.(Universidade Federal do Espírito Santo, 2022-09-02) Procopio, Erik Fissicaro; Scopel, Wanderla Luis; https://orcid.org/0000000220918121; http://lattes.cnpq.br/1465127043013658; https://orcid.org/0000000296190667; http://lattes.cnpq.br/; Caetano, Edson Passamani; https://orcid.org/0000000213102749; http://lattes.cnpq.br/9401385573887851; Souza, Angelo Malachias de; https://orcid.org/0000-0002-8703-4283; http://lattes.cnpq.br/8428074335454256; Amorim, Rodrigo Garcia; https://orcid.org/0000-0001-9611-8772; http://lattes.cnpq.br/0616474769970457In this thesis, the potential applicability of single layers of ferroelectric α-In2Se3 in photocatalytic hydrogen gas generation, via band gap engineering, and a topological phase transition induced by oxygen incorporation are explored via ab initio calculations, based on Density Functional Theory (DFT). For pristine In2Se3, our results indicate that via band gap engineering, under certain pH levels, the band alignment favors the use of this material in photocatalytic activity in water-splitting processes. Furthermore, motivated by recent research related to topological phase transitions in 2D materials by strain engineering and surface oxygen incorporation, a systematic study of the latter was employed to evaluate the possibility of such transition in this system. A handful of oxygen sources were used to determine if such reaction would occur: O2 molecules (triplet and singlet spin states), H2O molecules and atomic oxygen. Our ndings suggest that adsorption only occurs for singlet O2 and atomic oxygen. Moreover, total energy analysis for these sources indicate that there is no apparent active Se surface site selectivity, i.e., the adsorption might happen uniformly. The newly formed α-In2Se3O layer was shown to present non-trivial band topology which was then modulated by an external applied electric eld, highlighting a field-effect switching of the topological order.
- ItemEstudo teórico de heteroestruturas baseadas em materiais bidimensionais(Universidade Federal do Espírito Santo, 2018-10-26) Souza, Everson dos Santos; Scopel, Wanderlã Luis; Scopel, Wanderlã Luis; Amorim, Rodrigo Garcia; Souza, Fábio Arthur Leão de Souza; Canal Neto, Antônio; Alfonso, Jorge Luis Gonzalez; Caetano, Edson PassamaniThis thesis presents a theoretical investigation of two heterostructures based on 2D materials: (i) substitutionally cobalt-doped graphene bilayer (Co/GBL) on the Cu(111) surface [Co/GBL/Cu(111)] and (ii) a graphene-MoSe2 in-plane lateral heterostructure. The properties of these systems were studied through simulations of X-ray Absorption NearEdge Structure (XANES) spectroscopy and/or electronic structure methods based on Density Functional Theory (DFT). Our results indicate a magnetic switching phenomenon in the Co/GBL/Cu(111) system, that is, the capability of switch on and off the magnetization of the Co-doped graphene bilayer on Cu(111). This phenomenon is based on control of Co/GBL Cu(111) electronic charge transfer by an external electric field; which adjust the electronic occupation of the Co-3dz 2 and C-2pz orbitals near the Fermi level and, as a consequence, the magnetic properties of Co-doped graphene bilayer. In the graphene-MoSe2 system, based on energetic stability criteria for different structural models, we found that zigzag and Klein edges of graphene can serve as a nucleation site for the formation of energetically stable graphene-MoSe2 interfaces, where different structural morphologies are possible. For the energetically more likely interface geometries, were carried out additional characterizations of electronic and structural properties through simulations of XANES spectroscopy at the C K-edge. The analysis of the absorption spectra indicated the feasibility of identifying different interface geometries in the graphene-MoSe2 hybrid system from XANES spectroscopy measurements. The results also revealed that the local electronic and magnetic properties depend on the interface atomic structure. In particular, we found half-metallicity characteristic (conduction in only one of the two spin channels) at certain interface geometries, which has great potential for spintronics applications.