CMD30 FisMat2023 - Submission - View

Abstract title: Generalized plasma waves and linear response in bilayer superconductors
Submitting author: Niccolò Sellati
Affiliation: Sapienza University of Rome
Affiliation Address: Piazzale Aldo Moro, 5, Roma, RM
Country: Italy
Other authors and affiliations: Francesco Gabriele (Sapienza University of Rome), Claudio Castellani (Sapienza University of Rome), Lara Benfatto (Sapienza University of Rome)
Abstract
Thanks to strong developments in non-conventional THz spectroscopy, a great experimental interest keeps growing towards the low-energy collective excitations of anisotropic layered superconducting systems such as High-Tc cuprates. An outstanding example of such excitations is that of the Josephson plasma modes, plasma oscillations between layer sustained by the weak Josephson coupling of the superconducting sheets[1][2]. In bilayer cuprates, crystals with two superconducting planes per unit cell, the plasma oscillations are the cause of many remarkable properties that distinguish them from isotropic and single-layer superconductors[3][4]. Our work is aimed at providing an analytical theoretical framework able to describe the features of the plasma modes of such systems and that can also be used as a groundwork to explain the peculiar characteristics of their linear and non-linear optical response functions. The description of such oscillations in our framework is valid in all momentum regions and as such can be used to explain not only the results of the aforementioned THz experiments, but also of the high-energy spectroscopies like RIXS and EELS. Moreover, we were able to give a microscopical explanation to the unusual transverse plasma peak appearing in the real part of the optical conductivity[5], connecting its emergence to an internal short-range Coulomb interaction between the two planes of a unit cell having different values of the superconducting phase[6].
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  6. N. Sellati, F. Gabriele, C. Castellani, and L. Benfatto, preprint (2023)