Department of Materials Science
Single metal atoms confined in graphene have proven to be outstanding catalysts for various chemical reactions and promising candidates for gas sensing applications. However, it remains unclear whether their chemical activity is determined by the specific type of metal atom or is a direct consequence of the confinement itself.
Our research activities are focussed on the characterization of materials through photoelectron spectroscopy techniques. In these experiments we collect and analyse the electrons emitted by the sample due to the photoelectric effect upon exposure to various monochromatic light sources. The photon energies suitable to photoemission ranges from hard x-rays to UV, allowing for the extraction of different physical and chemical properties. All experiments are carried out in ultra-high-vacuum conditions (UHV), ensuring a perfect isolation of specimen surfaces from external contaminations.
The application of x-rays to photoelectron spectroscopy (XPS) allows for the identification of atomic species and their chemical bonding type. XPS can be applied to any UHV compliant sample and thus it is a fundamental tool for research, especially where the materials surfaces and interfaces are relevant. For example, XPS has been applied to semiconductors, oxides, solar cells, gas sensing materials, functionalized surfaces and many more. XPS analysis can be also extended to other properties, such as local crystal structure, depth profiling analysis, interface junction energy diagrams or evaluation of charge-transfer state of complex materials. We are also investigating the possibility to speed up and improve the XPS spectra analysis through machine learning techniques.
UV based electron spectroscopy (UPS) gives a better insight about the sample valence band, i.e. about the energy region where the actual chemical bond takes place. This technique can be applied to any conductive material, both crystalline or polycrystalline, or to characterize the properties of surface adsorbed molecules.
Furthermore, when carried out with a modern angle-resolved analyser (ARPES, angle-resolved photoelectron spectroscopy), this technique allows for the direct measurement of crystalline materials band structure. ARPES is then the best tool for the exploration of several interesting materials which display quantum properties, such as 2D compound (e.g., graphene), topological insulators and high temperature superconductors.
We are in the design stage of the future XPS-ARPES lab. The main goal is to provide an high performance tool, compatible with most of the department research topics, with free customization and expandability options. The system will include:
We will also consider to expand towards additional facilities, such as near-ambient pressure XPS (NAXPS) and hard x-rays photoelectron spectroscopy (HAXPES).
Prof. Giovanni Drera
Scintillator materials emit pulses of light when exposed to ionising radiation or high-energy charged particles. Today, brighter fast scintillators are needed for advanced applications to acquire data with high signal-to-noise ratio in short time windows, such as in time-of-flight positron emission tomography (ToF-PET) imaging for cancer.
Silicene, a two-dimensional form of silicon, has attracted significant interest for its potential in advanced technologies. Like graphene, it has a unique structure that allows electrons to move in interesting ways, making it highly compatible with existing semiconductor technologies. However, despite progress in creating and working with silicene, challenges remain—especially in finding suitable surfaces (substrates) to support its structure.
Electrochemistry combined with microbial life in the so called microbial bioelectrochemical systems can certainly being a power tool for degrading organics compounds in contaminated soils and transforming various pollutants into harmless compounds. In fact, the microbial degradation of pollutants can be enhanced when combined with electrochemical methods. The application of external potentials can certainly enhance the degradation shortening the operational time.
Our group is dedicated to the modelling and design of innovative quantum materials that exhibit promising functionalities (i.e. magnetism, ferroelectricity, multiferroicity, coupled spin/charge/orbital/lattice degrees of freedom), of interest for next-generation low-power spintronic devices.
At the heart of our research lies the use of first-principles simulations within density functional theory, enabling us to delve deeply into the structural, electronic, ferroelectric and magnetic properties of these materials. Complementing these ab-initio investigations, we frequently employ model Hamiltonian approaches and rigorous symmetry analysis to enrich and broaden our understanding.
Our main current focus is modelling two-dimensional magnets (i.e. NiI2, CrI3, CrGeTe3), atomically-thin layers that exhibit long-range magnetism and spin-orbit-induced phenomena. Another key area of interest lies in oxide-based perovskites, including manganites, particularly those characterized by a strong coupling between spin and dipolar degrees of freedom, leading to phenomena such as multiferroicity and magnetoelectricity.
We study the microscopic origin of complex spin textures (i.e. non-collinear, non-coplanar, helical, skyrmions, etc) and the possible coexistence of magnetic order with exotic phenomena, such as ferroelectricity, charge-order, k-dependent spin-splitting in the electronic structure of the compounds of interest.
The coexistence of multiple orders enhances the multifunctional capabilities of materials, enabling, for instance, the manipulation of spin degrees of freedom through the application of an electric field, one of the grand-challenges in spintronics.
Prof. Silvia Picozzi
Transition Metal Dichalcogenides (TMDs) are a versatile class of materials with immense potential for fields of application, from nanoelectronics and optics to sensing and catalysis. TMDs are inherently imperfect, containing defects such as vacancies and boundaries that significantly impact on their properties. Defects are often considered detrimental due to their negative effects on some materials’ properties like mechanical and chemical stability, or alterations in electrical transport.