In his thesis, Baldini used cutting-edge ultrafast spectroscopic tools, to explore the dynamical behavior of so-called “quantum materials”. This term refers to a wide class of solids that hosts exotic quantum phenomena of fundamental and technological interest. Notable examples of such exotic phenomena include high-temperature superconductivity, unconventional magnetism, and multiferroicity. More specifically, Baldini investigated the dynamical evolution of “collective excitations”. Among them, we find phonons (i.e. quanta of lattice vibrations in crystals), magnons (i.e. quanta of spin waves in magnets), plasmons (i.e. quanta of plasma oscillations in metals), and excitons (i.e. quanta of electronic energy in semiconductors). Understanding their dynamical behavior holds promise for future technology, especially in relation to solar energy conversion (photocatalysis, photovoltaics), biomedical sciences, magnetic data storage, and ultrafast signal processing.

Among the numerous results he obtained in his thesis, Baldini revealed the dynamics of phonons in high-temperature superconductors and unveiled the existence of a novel type of excitons in certain transition metal oxides. Besides their fundamental implications, these discoveries open avenues for novel applications. Indeed, phonons and excitons can sense the external environment and monitor fast dynamical phenomena occurring in devices. Furthermore, phonons and excitons can be controlled through other collective excitations or through external laser pulses. This, in turn, can lead to new functionalities in next generation devices based on these material systems.