Using Resonant Inelastic X-Ray Scattering to Study Quantum Materials

ABSTRACT

Modern light sources like the NSLS-II at Brookhaven National Lab deliver bright tunable photons in a wide range of energies from the THz regime up to 100 keV. This allowed the development of scattering techniques relying on the use of atomic resonances, enabling access to the electronic degrees of freedom in materials. Resonant Inelastic X-Ray Scattering (RIXS) is one of these techniques, and thanks to the massive development in instrumentation and theory is playing a significant role in the study of quantum materials with contributions in multiple fields such as superconductivity, quantum magnetism, 2D materials, and, lately, single photon emission. The sensitivity of RIXS to bosonic excitations of a different nature (spin, orbital, lattice, and charge) can provide microscopic information on materials as a function of energy and momentum. In my seminar, I will start by introducing RIXS its capabilities and limitations, followed by a description of the experimental components needed to perform high-resolution RIXS and the solution that we developed at BNL. I will then move forward by highlighting two scientific cases in different fields. The first will involve our investigations on quantum emitters in hBN, where we could unveil vibronic states and connect them to the signals detected in photoluminescence, possibly identifying N2 molecular vibrations as the key for the emergence of quantum emission. Secondly, I will conclude by highlighting one of our studies on excitons in 2D van der Waals magnets where we could detect their nature, evolution as a function of charge transfer energy (and hybridization), and their dispersion in momentum space.

[1] Ament et al., Rev. Mod. Phys. 83, 705

[2] Fan et al., unpublished

[3] Pelliciari et al., Nat. Mat. 23, 1230

[4] Occhialini et al., Phys. Rev. X 14, 031007 words.

BIOGRAPHY

Jonathan (Johnny) Pelliciari is a Scientist at NSLS-II, where he uses advanced scattering techniques (including Resonant Elastic and Inelastic X-Ray Scattering RIXS) to investigate the electronic properties of quantum materials. He got a Bachelor and Master degree in Chemistry at the University of Modena and Reggio Emilia (Italy) and a PhD in Experimental Condensed Matter Physics at the Paul Scherrer Institute and University of Fribourg/Freiburg (Switzerland). His research involves the study of electronic orders such as charge and spin density waves and the elementary (spin, charge, orbital, and lattice) excitations in superconductors, low-dimensional systems, and materials displaying metal-to-insulator transitions. Overall, his research interests span different physical phenomena, such as ultrafast phenomena, unconventional charge density waves, spin excitations, superconductivity, 2D van der Waals systems, spin liquids, and quantum emitters. He developed a laser-RIXS setup commissioned at the SIX beamline to study quantum materials and their ultrafast transitions.

He has several active collaborations with external universities and research institutes (CUNY, Stanford, MIT, Yale, Harvard, University of Zagreb, and PSI) on different projects.