Location: Room F3-106, IEF Building
Time zone: Brasília Time (BRT, UTC−3)
Date: 26 Nov 2025 – 13:30
Title: Research on Polycrystalline and Single-Crystalline CVD Diamond and DLC (Diamond-like Carbon) and the Path to Innovation
Speaker: Prof. Dr. Vladimir Jesus Trava-Airoldi (INPE)
Abstract:
Studies in the areas of CVD diamond and DLC have attracted considerable interest in academia and industry due to their strong scientific and technological appeal. In this lecture, the main results regarding the production of these materials will be presented, both at the National Institute for Space Research (INPE) and at the company CVD Vale Diamantes. Possible technological applications and innovation routes will also be discussed, highlighting the importance of the space sector and its contribution to national development. Basic concepts of value generation and the selection of projects capable of interacting with society will be addressed. Concrete examples of technology transfer involving polycrystalline and single-crystalline CVD diamond as well as DLC will be presented, together with perspectives for advanced entrepreneurship in Brazil and abroad.
Date: 12 Nov 2025 – 13:30
Title: Assessing Device-Limiting Features in Solar Cells by Correlative Electron Microscopy
Speaker: Prof. Dr. Daniel Abou-Ras (USP-Lorena)
Abstract:
Photovoltaic solar cells are among the most important renewable energy technologies, with substantial contribution to electrical energy production in Brazil. This seminar will provide an overview of photovoltaic solar-cell technologies and the limitations affecting device performance. In particular, it will be shown how correlative electron microscopy can be employed to assess the microscopic origins of these limitations. Special attention will be given to the role of grain boundaries in solar cells.
Date: 29 Oct 2025 – 13:30
Title: From Turbulent Fluctuations to Coherent Structures: Gradient Pattern Analysis and Deep Learning Approaches in Complex Systems
Speaker: Dr. Reinaldo R. Rosa (Applied Research and Technological Development Coordination, INPE-MCTI)
Abstract:
This talk presents two ongoing R&D projects that explore the emergence and detection of coherent structures in complex physical systems through the combined use of gradient pattern analysis (GPA) and deep learning techniques. Both projects aim to understand how spatiotemporal fluctuations evolve into coherent structures and how these can be automatically recognized in large-scale simulations. The first project focuses on multiplicative cascade simulations based on the p-model, which provides a framework for studying hierarchical energy transfer and intermittency in turbulent-like systems. The second project investigates three-dimensional coherent structures in reactive–diffusive systems modeled by the Complex Ginzburg–Landau equation. By combining GPA-based descriptors with neural-network classification and feature extraction, these projects establish an interdisciplinary approach that bridges nonlinear physics, computational modeling, and artificial intelligence.
Date: 15 Oct 2025 – 13:30
Title: Growth of Ultrananocrystalline Diamond (UNCD) on KOH-Textured Silicon
Speaker: Dr. Úrsula Andréia Mengui (ITA)
Abstract:
A well-known solution for anisotropic wet etching of silicon is aqueous potassium hydroxide (KOH). Many studies have been conducted to understand and control the roughness of silicon (100) surfaces, which exhibit rapid etching, as well as the formation of micropyramids with rectangular or octagonal bases. Wet anisotropic chemical etching is widely used for silicon processing and has applications in microelectromechanical systems (MEMS), microvalves, optical switches, and alignment channels. Ultrananocrystalline diamond (UNCD) films were grown using a gas mixture of Ar/CH4/H2, producing films with grain sizes around 3–5 nm and minimal graphitic impurities. These films present remarkable properties such as extreme hardness, low friction coefficient, and large surface area, making them promising for tribological and electrochemical applications. This work investigates different silicon morphologies obtained by wet chemical texturing and analyzes the morphology and structure of UNCD films grown on micropyramidal silicon substrates.
Date: 8 Oct 2025 – 13:30
Title: Topology and Interactions at 1.58 Dimensions
Speaker: Prof. Dr. Cristiane Morais Smith (Institute for Theoretical Physics, Utrecht University, the Netherlands)
Abstract:
We know how topological insulators behave in 1, 2, and 3 dimensions, but what happens in between? In this talk, theoretical and experimental results on ultranarrow germanene nanoribbons will be presented, showing the transition from one-dimensional topological edge states to zero-dimensional end states when the ribbon width is reduced below 2 nm. The talk will also discuss the topological properties of electrons in single-layer bismuth fractals with dimension d = 1.58 and present theoretical results on the Hubbard model in fractal geometries. Finally, ongoing studies involving fractal structures of Rydberg atoms trapped by optical tweezers will be discussed.
Date: 1 Oct 2025 – 13:30
Title: Discrete and Continuous Scale Invariance in the Quantum Few-Body Problem
Speaker: Dr. Rafael Mendes Francisco (ITA)
Abstract:
Efimov universality describes three-body systems close to unitarity, in which large scattering lengths make their properties essentially independent of the details of short-range interactions. This regime is characterized by a discrete scale symmetry reflected in a geometric spectrum of trimers. In ultracold atomic gases, interactions can be tuned to the resonant regime using external magnetic fields. This work explores how the Efimov spectrum responds to extreme confinement modeled through a continuous effective dimension. It is shown that when a critical dimension is reached, discrete scale invariance is suppressed and replaced by continuous scale invariance. Nuclear physics provides a natural analogue of this phenomenon in two-neutron halo nuclei, whose universal properties can be analyzed within the Efimov framework.
Date: 17 Sep 2025 – 13:30
Title: Unveiling Chaos from Climate to the Universe: An Application of Fourier Neural Operators
Speaker: Dr. Roberta Duarte Pereira (ITA)
Abstract:
The Fourier Neural Operator (FNO) is a neural network designed to solve partial differential equations in complex systems. Unlike traditional neural networks that learn pointwise mappings, the FNO operates in Fourier space and efficiently captures global and multiscale patterns. Variants such as the Adaptive Fourier Neural Operator (AFNO) and the Spherical Neural Operator (SNO) extend this approach. One application is the FourCastNet model, capable of generating forecast ensembles by exploring parameter space and perturbations. These techniques represent a new generation of models capable of addressing chaotic and nonlinear systems, offering a promising alternative for simulations of fluids, plasmas, and climate prediction.
Date: 3 Sep 2025 – 13:30
Title: Technologies for the Fabrication of Millimeter-Wave (mmW) Devices
Speaker: Dr. Robert Aleksander Gavidia Bovadilla (ITA)
Abstract:
The rapid development of telecommunications increases the demand for faster, more compact, and energy-efficient wireless systems. Since conventional frequency bands are already saturated, millimeter waves (30–300 GHz) emerge as an attractive solution with applications in automotive radars, real-time video transmission, and RF imaging systems. This presentation will discuss beamforming techniques and their implementation, including phase shifters and Butler matrices, as well as fabrication technologies based on silicon and alternative substrates such as nanoporous alumina membranes. Devices based on slow-wave transmission lines will also be presented, highlighting their relevance for future high-frequency communication systems.
Date: 20 Aug 2025 – 13:30
Title: Search for New Physics with Neutrino Masses and Symmetries
Speaker: Prof. Dr. Caio Licciardi
Abstract:
Over the past decades, neutrinos have quietly transformed our understanding of the universe. These particles interact very weakly with matter, yet their properties have inspired fundamental ideas in particle physics. From the discovery of neutrino oscillations to the possibility that neutrinos may be their own antiparticles, these particles continue to challenge the Standard Model. In this seminar, I will present work within the nEXO and Hyper-Kamiokande collaborations, which aim to investigate neutrinoless double beta decay and neutrino oscillations, searching for CP violation in the lepton sector and probing the nature of neutrino masses.
Date: 13 Aug 2025 – 13:30
Title: Bose–Einstein Condensates: Quantum Turbulence as a Prototype of Out-of-Equilibrium Many-Body Quantum Systems
Speaker: Prof. Dr. Vanderlei Salvador Bagnato
Abstract:
In this seminar, we will introduce the topic of Bose–Einstein condensates and the generation of quantum turbulence in this superfluid. We will then study the relaxation of turbulence as an example of the dynamics of closed quantum systems out of equilibrium and their route toward thermalization. We will discuss the observation of distinct stages during the relaxation of turbulence and the re-emergence of the condensate in equilibrium. Our results show a direct cascade of particles from low to high momenta, a consequence of energy injection into the system, displaying a universal scaling law. This stage is followed by an inverse cascade of particles responsible for repopulating the previously perturbed condensate. Both cascades can be explained through self-similar solutions provided by wave turbulence theory. These results provide important insights into the relaxation stages of out-of-equilibrium many-body quantum systems. Finally, we will analyze new experiments currently underway and novel findings related to quantum systems out of equilibrium.
