A research team which includes a large group of researchers from CNR-SPIN, CNR-IOM together with scientists of University Ca’ Foscari, University of Salerno, and MagTop Research Centre in Warsaw, as well as other national and international partners, has discovered a new state of matter characterized by the existence of a quantum phenomenon dubbed “spin-orbital chiral current”. These currents are generated on an atomic scale by a chiral cooperative movement of electrons, unlike conventional magnetic materials whose properties originate from the quantum characteristic of an electron known as spin and their ordering in the crystal.
Chirality is a property of extreme importance in science. In the quantum phenomenon discovered, the chirality of the currents was detected by studying the interaction between light and matter, in which a suitably polarized photon can emit an electron from the surface of the material with a well-defined spin state.
Born from a theoretical prediction, this study directly and for the first time verified the existence of this quantum state, until now enigmatic and elusive, thanks to the use of the Italian Elettra synchrotron. Until now, knowledge about the existence of this phenomenon was in fact limited to theoretical predictions for some materials. Of great importance for the discovery has been the use of quantum materials which were manufactured, optimized and analyzed with a high level of control.
The new discovery significantly enriches our knowledge on quantum materials, on the search for chiral quantum phases and on the phenomena that occur at the surface of materials. The existence of these quantum states may pave the way for the development of a new type of electronics that employs chiral currents, with the chirality rooted in the electron spin and orbital angular momentum, as information carriers in place of the electron's charge. Furthermore, these phenomena could have an important implication for future applications based on new chiral optoelectronic devices, and a great impact in the field of quantum technologies for new sensors, as well as in the biomedical and renewable energy fields.
The research results have been published in the journal Nature – “Signatures of a surface spin–orbital chiral metal” (https://doi.org/10.1038/s41586-024-07033-8), by Federico Mazzola, Wojciech Brzezicki, Maria Teresa Mercaldo , Anita Guarino, Chiara Bigi, Jill A. Miwa, Domenico De Fazio, Alberto Crepaldi, Jun Fujii, Giorgio Rossi, Pasquale Orgiani, Sandeep Kumar Chaluvadi, Shyni Punathum Chalil, Giancarlo Panaccione, Anupam Jana, Vincent Polewczyk, Ivana Vobornik , Changyoung Kim, Fabio Miletto-Granozio, Rosalba Fittipaldi, Carmine Ortix, Mario Cuoco, and Antonio Vecchione