In the last decades, several 2D materials (e.g., graphene, hexagonal boron nitride, transition metal dichalcogenides, artificial organometallic networks - MOFs) have been intensively studied, revealing interesting physical phenomena and unique electronic, optical, and catalytic properties. These materials are promising for innovative technological applications, such as new catalysts, sensors, electronic and photonic devices, etc. A fascinating technique for preparing these materials is the so-called on-surface synthesis (SS) [1,2]. SS is a bottom-up technique that uses specifically “designed” precursors as molecular building blocks (such as pieces of a LEGO) to create, on-demand, new materials with the desired atomic and electronic structure. With this, we can, for example, build model systems (toy models) that allow exploring singular properties, such as new semiconductors, photonic lattices, or artificial magnetic lattices.

The Surface Physics Group (GFS) at UNICAMP has used SS in recent years in the epitaxial growth of different members of these 2D material families [3-8]. In this work, I will show recent examples in which we apply different growth and functionalization strategies to produce new semiconductors [7] and organometallic networks [3-5,8], whose electronic and atomic structures have been characterized by X-ray photoemission spectroscopy (XPS) and scanning tunneling microscopy/spectroscopy (STM/STS) techniques.

References

[1] Mengqi Zeng, et al., Chemical Reviews 118 (13), 6236-6296 (2018).

[2] Sylvain Clair, et al., Chem. Rev. 119, 4717-4776 (2019).

[3] M. Lepper et al., Angew. Chem. Int. Ed.. 57, 10074-10079 (2018).

[4] Juan Carlos Moreno-López, et al., Chemistry of Materials 31 (8), 3009-3017 (2019).

[5] Alisson Ceccatto dos Santos, et al., Chemistry of Materials 32 (5), 2114-2122 (2020).

[6] Gabriela Moura do Amaral, et al., Applied Surface Science, 538,148138 (2021).

[7] Nataly Herrera-Reinoza, et al., Chemistry of Materials 33, 2871-2882 (2021).

[8] Alisson Ceccatto dos Santos, et al., J. Phys. Chem. C 125, 31, 17164–17173 (2021).

Acknowledgments

This work was financially supported by FAPESP, CNPq, and CAPES (PROBRAL DAAD-CAPES).

There are many opportunities for physics graduates in the private sector. These in general fall into a few broad categories. I will give a general overview and present the pros and cons of each from a physicist point of view. In addition, I will describe the lessons from my experience as an interviewee and interviewer for private sector jobs, and give guidance for job interview preparation and the transition in general. In that I will include links to training and preparation resources.

The volume of data generated in the world has increased exponentially, and in the last 10 years, it is no longer possible to store all the data generated. In 2020, about 40 trillion gigabytes of data were generated. But, after all, what does it matter in the academic world? What does this impact on the business of a small, medium or large company? How can this impact our life? The answer starts with the search for people with technical training to work in the processing of all this volume of data. They are professionals with the ability to translate information into strategic decisions, essential within companies, in research and innovation. At this moment, we are faced with a major problem: there are not enough people in the world with enough technical skills, today and in the next 10 years, to work in the areas of data and generate value with them. Why such an intense search for professionals who work with data? Companies have already understood that the data driven culture generates an increase in revenue, cost reduction and improvement in people's quality of life. And when we say “companies” we mean all market segments: industry, health, retail, finance, e-commerce, wholesale, among others. There are almost 20 million companies in Brazil alone. Imagine 1% of them hiring technology professionals, we are talking about 2 thousand vacancies, but we already know that the projection is 700 thousand vacancies from today to the next 5 years. With the information mentioned, the question remains about how the academic area, universities, faculties, technical institutes and schools can be structured to technically train all this volume of people. In addition, how to generate a greater bond between educational institutions and companies so that this process can be accelerated and optimized for people who intend to enter the job market. The idea of this seminar is to present how big data and analytics are being implemented in real cases in companies from different sectors. How Data Science, Data Engineering, Machine Learning Engineering, DevSecOps Engineering MLOps, DataOps and Cloud Architecture are being structured.

In this talk, after an introduction to thermoelectric (TE) properties, we analyze recently synthesized graphene nanoribbon (GNR) heterostructures that are obtained as extensions of pristine  armchair graphene nanoribbons (AGNRs). After simulating their band structure through a nearest-neighbor tight-binding model, we use the Landauer formalism to calculate the necessary TE coefficients, with which we obtain the electrical conductance G, thermopower S, thermal conductance Ke, and figure of merit ZT (using literature results for the phonon thermal conductance Kph), at room temperature. We then compare the results for the nanoribbon heterostructures with those for the pristine AGNR nanoribbons. The comparison shows that the metallic AGNRs become semiconducting (with much higher ZT values) after the inclusion of the extensions that transform them into heterostructures and that some heterostructures have higher values of ZT when compared to the semiconducting pristine AGNRs from which they  have originated.

In this talk, we will present some recent results on the quantum transport of electrons through quantum dots and quantum rings coupled to normal and topological superconductors. In addition, we will discuss the effects of Andreev reflections and Majorana zero modes on the transport and electronic properties of the systems.

[1] Medina, Fabian; Martinez, Dunkan; Diaz-Fernandez, Alvaro; Dominguez-Adame, Francisco;  Rosales, Luis; Orellana, Pedro A.  SCIENTIFIC REPORTS 12 1071 2022
[2] Gonzalez, IA ; Pacheco, M; Calle, AM; Siqueira, EC ; Orellana, PA  SCIENTIFIC REPORTS 11 3941 2022

This talk is divided in two parts. In the first part, I´ll briefly describe the Brazilian Nanotechnology National Laboratory (LNNano), an open facility for research and innovation in the field of nanoscience and nanotechnology located in Campinas, Brazil, in the same campus as three other National Laboratories which include Sirius, a 4th generation synchrotron facility. In the second part, I´ll discuss our recent joint theory/experiment work on the formation and rupture of monatomic ZrO2 wires.

A bound state in the continuum (BIC) is a discrete energy level within the continuous portion of a spectrum. BICs have been identified in optical systems, and the findings have led to  advances in telecommunication technology. Less productive has been the search in nanostructured devices. The subject of this talk, a system belonging to the latter class, has attracted some attention in the last two decades. The device comprises a quantum wire coupled to two identical quantum dots and is modelled by a two-impurity Anderson model with a single conduction channel. The symmetry with respect to dot exchange splits the spectrum of the model Hamiltonian into even and odd sectors; the dot orbitals form a bonding (even) level and an antibonding (odd) level. While the antibonding orbital constitutes a BIC in the noninteracting model, the Coulomb interaction hybridizes it with odd eigenstates in the continuum. This hybridization accurately accounted for, a numerical renormalization-group computation of the spectral density for the antibonding orbital will be shown to pinpoint a virtual BIC in the low-energy spectrum. The BIC is virtual because the Anderson catastrophe forbids transitions to the lowest level in the even sector of the spectrum. Particle-hole excitations allow transitions to  higher even states and broaden the spectral density asymmetrically into a divergent power-law akin to an x-ray edge singularity. This smearing can nonetheless be avoided: additional numerical results will be presented to show that adequate tuning of a gate potential avoids the catastrophe, washes out the contribution  from particle-hole excitations, and recovers the infinitely sharp line distinctive of a BIC.

Two-dimensional systems (2D) are a 'pure surface', and its properties can be adjusted by modulating its environment. For instance, depositing a 2D system over different substrates, stacking them in heterostructures, adding a twist angle between different layers, or depositing molecules 
onto it. In this talk, we will discuss all these examples through nano-Raman spectroscopy. Such environmental perturbations cause phonon and electron localization at a nanometer scale; the consequences and effects of such perturbations on the 2D systems are then understood through their atomic modelling. 

A metal can be driven to an insulating phase through distinct mechanisms. A possible way is via the Coulomb interaction, which then defines the Mott metal-insulator transition (MIT). Another possibility is the MIT driven by disorder, the so-called Anderson MIT. In this talk I will discuss the use of quantum entanglement to identify and characterize the MIT in disordered Hubbard chains with interacting fermions — thus comprising the Mott-Anderson physics [1,2]. 

[1] Phys. Rev. B 104, 134201 (2021).
[2] arXiv: 2202.01557 (2022). 

Polymers are complex molecules having a reach set of topologies that affect their diffusive behavior.  Understanding how polymers diffusive has been a topic of great scientific and applied interest on a variety of fields.  As an example, a theoretical model of a polymer can as a paradigm to other long molecules, such as those commonly found in biology.

Recent research interest has shifted from bulk studies, where there is more complete understanding to studies on surfaces. I will present some recent work based of polymer diffusion on more realistic cases, including preliminary results for bioapplications.