Condensed matter physics has advanced rapidly in recent decades, driven by the development of increasingly precise nanofabrication techniques. Today, it is possible to produce and characterize structures with dimensions of just a few nanometers—i.e., at scales only slightly larger than the atomic scale—making it possible to control electronic, magnetic, and optical properties in unprecedented ways.

 

More recently, a new class of two-dimensional systems based on exfoliable materials, such as transition metal dichalcogenides (TMDs), has gained prominence. Because they consist of weakly bonded layers, these materials can be isolated as monolayers and stacked into van der Waals heterostructures, opening up opportunities to explore new regimes of quantum confinement, symmetry effects (or symmetry breaking), and strong spin–orbit coupling. In this context, it has become possible to investigate a variety of mechanisms for converting between spin and charge currents—including Hall-type effects (such as spin Hall, orbital Hall, and valley Hall) and the Rashba–Edelstein effect at interfaces.

 

Among the most active topics in this area is spin-related electronic transport, which underpins so-called spintronics. The central idea is to use not only the electron’s charge, but also its spin degree of freedom to generate, manipulate, and detect currents and magnetic states, with the potential to reduce energy dissipation and expand device functionalities. Technological applications are broad and promising, ranging from high-density magnetic recording technologies and sensors to architectures based on magnetic random-access memory (MRAM), as well as the development of magnetic logic gates and transistors aimed at more efficient computing and data storage.

 

Main projects:

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- Spin/orbital angular momentum pumping in two-dimensional systems: Spin pumping is one way to generate a spin-polarized current from a hetero-structure composed of a magnetic film in contact with a non-magnetic material. The major challenge is to understand what actually happens at the interface, and two-dimensional materials obtained by CVD or by different exfoliation methods (mechanical, chemical, etc.) are particularly well suited to advance in this direction. We have several research fronts involving interfaces with semiconducting materials, and the influence of light on the conversion processes from spin/orbital current to charge current.

 

- Magnetic properties of two-dimensional materials obtained from van der Waals materials: Transition metal dichalcogenides (TMDs) exhibit very rich electronic properties—from insulators to metals and even superconductors—and they can be exfoliated, allowing the production of very thin flakes, including monolayers. My proposal is to investigate several magnetic properties, including Tc in monolayers, anisotropies, and spin/orbital angular momentum injection effects in TMDs in contact with ferromagnets (e.g., YIG), combining techniques such as focused MOKE and anomalous Hall measurements to understand spin/orbital-to-charge conversion mechanisms (SHE, OHE, VHE, Rashba–Edelstein). The ultimate goal is to map the relationships between structure, magnetic and electronic properties, and spin–orbit coupling in TMDs in order to identify promising conditions for the fabrication of spintronic and opto-spintronic devices.

 

Equipment: We have a magneto-optical measurement system capable of measuring hysteresis loops of objects down to a few micrometers in size; a broadband ferromagnetic resonance measurement system from 1 to 20 GHz; a magnetoresistance measurement system down to 6 K; as well as access to CBPF shared infrastructure such as vibrating sample magnetometers and SQUID magnetometers. Some photos can be seen here.

 

Collaborators: My main collaborators at CBPF are Flávio Garcia, Eduardo Bittar, Damian Dugato, João Paulo Sinnecker, Carmem Gilardoni, Obed Alves, Nicholas Prestes, Ramon Cardias, Flaviano Santos, and Tatiana Rappoport. This also includes Roberto Bechara and Marcio Costa from UFF, and Alexandra Mougin from Université Paris-Saclay.