The DFA Talks, as the name says, are talks about DFA, the Physics and Astronomy Department of the Faculty of Sciences of the University of Porto. There are four research institutes/centres carrying out their research at DFA and we want to show them and their work!
Each institute will present itself and some of its research during one hour. The time schedule of each institute will be announced closer to PLANCKS, but below, you can already find some of the speakers and abstracts.
The Instituto de Astrofísica e Ciências do Espaço (IA) is a research infrastructure with a national dimension. Currently the institute is the largest research unit of the area of Space Sciences in Portugal, being responsible for the majority of the national productivity in international ISI journals in this area. The research and development effort at the IA includes most of the topics presently, and for the next decade, at the forefront of research in Astrophysics and Space Sciences, from the Solar System to the large-scale properties of the Universe, complemented by work on instrumentation and systems with potential use in Astronomy and Astrophysics projects.
Astrophysics training and research opportunities at CAUP
Prof. Carlos Martins
I will present the Centre for Astrophysics of the University of Porto (CAUP), including its structure and relation to the University of Porto (UP) and IA and its main research areas. I will then discuss in more detail the training and research opportunities for undergraduate, masters and doctoral students, including the activities of our Training Unit, which I coordinate.
ELT: How to Prepare a Revolution
Prof. Carlos Martins
The Extremely Large Telescope (ELT) is a revolutionary ESO scientific project for a 39m ground-based telescope. When it’s operational it will be the world’s largest optical/IR telescope, enabling us to tackle the grand challenges of modern astronomy and physics. I will describe its key science goals (with some emphasis on fundamental cosmology) together with some of the technological challenges of the project and its spin-offs. Being a member of the ELT Project Science Team since its creation in 2012, I will also try to give you an inside view of the development of a 20-year billion Euro scientific project.
The Institute of Physics for Advanced Materials, Nanotechnology and Photonics (IFIMUP) is a physics Research Unit of the University of Porto, operating at Faculty of Sciences aiming to carry out research over a wide range of topics focused on the innovative physical properties of materials at different scales, boosting the development of new technologies in order to contribute to solve today’s Grand Challenges.
Following an introduction of the institute and of the several opportunities here, there will be talks by junior and senior researchers about a wide range of topics.
IFIMUP and its opportunities
Prof. João Pedro Araújo
The main research activities carried out at IFIMUP will be presented, as well as some of the research opportunities that exist at IFIMUP.
Printing the Future with Flexible Sensors
Dr. Ana Pires, Junior Researcher
Flexible printed sensors represent a growing worldwide market with a CAGR of up to 28% of year, ranging in applications from human-machine interfaces to environmental sensing. At IFIMUP, printed electronics have been used in several areas, including electronic textiles, energy harvesting systems, electronic tattoos, etc. Through the emergence of nanomaterials and their improvement of performance, innovative devices are being produced. The use of plastic substrates or textiles offers manufacturing advantages allied with excellent mechanical flexibility, weight reduction, and adaptability. In this talk, the 5-years IFIMUP working and knowledge in printing and flexible sensors will be presented.
Magnetic nanostructures for biomedical applications
Dr. Célia Sousa, Senior Researcher
Magnetic nanostructures have been widely studied due to its potential applicability into several research fields such as data storage, sensing and biomedical applications. Focusing on the biomedical aspect, few new approaches on cancer therapy are deserving of mention: magnetic fluid hyperthermia, drug targeting and magneto-mechanically induced cell death . In this talk, the most recent IFIMUP results in this field will be presented from the micromagnetic simulations of high-aspect-ratio nanowires and vortex nanodiscs, to their functionalization, cell internalization and biocompatibility.
1 L. Peixoto, R. Magalhães, D. Navas, S. Moraes, C. Redondo, R. Morales, J. P. Araújo, C.T. Sousa, Magnetic nanostructures for emerging biomedical applications. Appl. Phys. Rev., in press (2019).
Improving magnetoelectric multiferroic materials via atomic substitution, strain engineering and ultrafast light-pulses
Dr. Rui Vilarinho, Junior Researcher
Magnetoelectric coupling in multiferroics is a Holy Grail of solid-state physics, yet they are scarce. Multiferroics are materials that show more than one ferroic order, i.e., a coexistence of either ferro- or antiferro-magnetism, -electricity or -elasticity. Among them, the coexistence of magnetic and polar orders is the most interesting for applications, in particular when there is a cross-coupling between them, designed as magneoelectricity, meaning the magnetic order is sensitive to an applied electric field and the polar order sensitive to an applied magnetic field. The main mechanism that gives origin to magnetoelectric multiferroics is the stabilization of a spatially varying magnetization (i.e., modulated), whose magnetic order not only breaks time reversal but also breaks the spatial inversion, needed for ferroelectricity to emerge. Still, very few materials present it and the magnetoelectric coupling is usually small [1,2].
At IFIMUP, the group of Polarizable Materials and Functional Nanostructures has a research vector dedicated to improving the properties of magnetoelectric multiferroics. We have been successful in obtain new multiferroic materials by tailoring the crystallographic structures via atomic substitution or thin-film strain engineering to tune the magnetic interactions toward modulated magnetic orderings [3–5]. We were also successful in increasing the magnetoelectric effect in a well-known multiferroic (TbMnO3) through the introduction of small quantities (below 5%) of Fe spins that are highly sensitive to applied magnetic field . Finally, in collaboration with the “Ultrafast Lasers and Magnetodynamics Spectroscopies” also from our Institute, we are now starting a new paradigm-shifter research field known as dynamic multiferroicity, which consists in using the electric field of ultrafast light pulses to coherently induce suitable non-equilibrium atomic movements that generate new time-dependent ferro-electric and ferro-magnetic states, otherwise not accessible at equilibrium thermodynamic conditions.
1 N.A. Spaldin, S.-W. Cheong, and R. Ramesh, Phys. Today 63, 38 (2010).; 2 N.A. Spaldin and R. Ramesh, Nat. Mater. 18, 203 (2019).; 3 R. Vilarinho, et al., Solid State Commun. 208, 34 (2015).; 4 J. Oliveira, et al., Phys. Rev. B 84, 094414 (2011).; 5 J. Agostinho Moreira, et al., Solid State Commun. 151, 368 (2011).; 6 R. Vilarinho, et al., J. Magn. Magn. Mater. 439, 167 (2017).
“Centro de Física do Porto” (CFP) is the University of Porto unit of the research center CF-UM-UP (Centro de Física das Universidades do Minho e do Porto). The unit is located in the Physics Department of the Faculty of Sciences, and is fully devoted to research in theoretical physics, in the broad area of Quantum Physics and Fields in High Energy and Condensed Matter, exploring synergies between theorists of different fields.
Theoretical physics research at University of Porto
Prof. Eduardo Castro
A short presentation about the main research activities developed at the Centre of Physics of Porto (Centro de Física do Porto – CFP).
How to learn about quantum gravity by studying magnets
António Antunes, PhD student
Conformal field theories (CFTs) are universal objects which describe the physics of many different realms, including statistical mechanics, condensed matter physics, particle physics and string theory. Starting from the simple example of a magnet, we will go through the basics of CFTs with an emphasis on the physical principles of conformal invariance, unitarity and Bose/Fermi symmetry which give rise to the conformal bootstrap philosophy. This approach, based only on elementary consistency requirements, allows us to solve otherwise intractable systems with unprecedented accuracy. Finally, we will sketch the relation between CFTs and theories of quantum gravity.
From Fundamental Physics to Climate Change
Prof. Orfeu Bertolami
In this talk two issues of fundamental physics will be discussed, namely a proposal for dark matter and an alternative theory of gravity. It will be also shown how fundamental physics can provide an approach to understand the evolution of the Earth System driven by the human action in the Anthropocene.
What can Computers Tell us about the Quantum Mechanics of Disordered Electrons?
João Pires, PhD student
Most of our knowledge on the quantum physics of electrons in crystalline matter is based on Bloch’s Theorem . This important result states that electrons move like plane-waves across any spatially periodic potential and forms the basis of the electronic band theory of solids. Despite its success in explaining most properties observed in real-life conductors and semi- conductors, exceptional phenomena are known to be caused by (the ubiquitous) deviations from a perfect crystalline order. Paradigmatic examples of disorder-controlled physics phenomena can be traced back to the proposals of P. W. Anderson , who discovered that disorder can induce metal-to-insulator transitions caused by localisation of eigenstates . Over the years, many other examples where found, from the emergence of sample specific mesoscopic current fluctuations  to the quantised Hall effect in two-dimensional electron gases .
In this talk, I will briefly review important disorder effects in both static and transport properties of materials, providing some guidelines on current research trends in the subject [11-12]. The “mantra” of this presentation will highlight the central role of computer simulations in the investigation of disorder effects in condensed matter. This fact will be illustrated by specific examples off some recent work [6-12] done within the condensed matter theory group of CFP. Some of these results share strong ties with the ongoing development of theQuantumKITE , an open-source software capable of an exceptionally efficient numerical study of non-interacting disordered quantum matter.
1 Felix Bloch, Zeitschrift für Physik 52 (7–8): 555–600 (1928) 2 P. W. Anderson, Physical Review 109, 1492 (1958); 3 F. Evers and A. D. Mirlin, Reviews of Modern Physics 80, 1355 (2008); 4 P. A. Lee and A. Douglas Stone, Physical Review Letters 55, 1622 (1985): 5 Klaus von Klitzing, Reviews of Modern Physics 58, 519 (1986); 6 S. M. João et al. Royal Society: Open Science 7,191809 (2020); 7 N. A. Khan et al. Journal of Physics: Cond. Matt. 31 (17), 175501 (2019); 8 J. P. Santos Pires et al. Physical Review B 99 (20), 205148 (2019); 9 S. M. João et al. Journal of Physics: Cond. Matt. 32 (12), 15501 (2019); 10 J. P. Santos Pires et al. Physical Review B 101 (10), 104203 (2020); 11 M. Gonçalves et al. Physical Review Letters 124 (13), 136405 (2020); 12 J. P. Santos Pires et al. Physical Review Research 3 (1), 013183 (2021)
INESC TEC (Institute for Systems and Computer Engineering, Technology and Science) is a private non-profit research institution, dedicated to scientific research and technological development, technology transfer, advanced consulting and training, and pre-incubation of new technology-based companies.
The Centre for Applied Photonics (CAP) is one of the 13 R&D Centres of INESC TEC. CAP performs R&D in applied photonics, principally focusing on optical fibre technology. CAP is oriented towards applied research and development in optical fibre sources, optical fibre communication, optical fibre sensors and microfabrication (thin films and integrated optics). In this session, you will discover CAP and some of the research being done in this centre.
Optical Analogues in Nematic liquid crystals
Tiago Ferreira, PhD Student
Light propagating in nonlinear optical materials, with local and nonlocal nonlinearities, brought the possibility of emulating quantum fluids in experimentally accessible setups. Indeed, a light beam propagating in these materials can be interpreted as a fluid, where the nonlinearity of the medium mediates the required interactions between the photons and the diffraction in the transverse plane to the propagation gives the effective mass of the fluid. This fluid interpretation has allowed the production of superfluid-like flows to emulate phenomena characteristic of these flows, such as drag-force cancelation or vortex nucleation, as well as the emulation of some gravitational phenomena. Such experiments can be performed with a variety of optical materials, however, at our research group, we have been exploring the possibility of using nematic liquid crystals, which are new in this context. Nematic liquid crystals are a nonlocal optical material that offers external mechanisms that can be used to tune their nonlinear response. This is done by applying an external electric field, and this property makes these materials very interesting for implementing optical analogues.
In this presentation, I will explore how nematic liquid crystals can be used to produce fluids of light and observe superfluid effects, such as the drag-force cancellation and the emission of quantized vortices, or to create and study analogues of turbulent regimes, and even investigate non-minimal coupled gravity models. This work is supported by high-performance solvers based on GPU supercomputing for the generalized nonlinear Schrödinger equation developed at our research group.
Vernier Effect: A Path for Giant Sensitivity
Paulo Robalinho, Research Assistant
The market for optical fiber sensors requires the study of new ultra-sensitive sensors with a wide range of applications in several areas of engineering. For this, the interest in developing more sensitive materials emerges, but it is not the only way to increase sensitivity. This presentation will be marked by the introduction of the Vernier effect in optical sensing. This effect consists in the measurement of the beat patterns that arise from the overlapping of different signals. Presently, its application allows colossal sensitivity, essential in sensors for micrometric and
Ultrafast Laser Micromachining and Applications in Optofluidics
João Maia, PhD Student
Ultrafast laser inscription is a versatile microfabrication technique capable of surface and volume processing of different classes of materials, such as glasses, crystals or polymers. In short, by tightly focusing a fs-laser beam inside a transparent medium, their high peak intensity can trigger a local modification in the structural properties of the material confined to a micrometric-sized volume. In fused silica, these modifications can be exploited to form either integrated optical devices or microfluidic systems or, owing to the confined nature of the laser-induced modification, optofluidic devices which combine both types of systems in a single substrate and in a user-defined three-dimensional architecture. This talk will present an overview of the work developed at INESC TEC concerning glass machining. Recent results on optical sensing based on a monolithic whispering-gallery mode resonator will also be presented.