Through a collaborative effort led by Prof. Stefano Lupi and Dr. Salvatore Macis from the Department of Physics at Sapienza University and teams from the Minnesota University and other institutions, the optical properties of PdCoO2 and PdCrO2 have been investigated. These delafossites exhibit a unique feature, a dual optical hyperbolicity, a phenomenon where two distinct spectral regions support hyperbolic behavior in their dielectric response. Specifically, both materials display a narrow Drude–Lorentz hyperbolic regime in the mid-infrared and an exceptionally broad Drude–Drude hyperbolic region that extends from the infrared into the visible. The optical measurements reveal record values of hyperbolic quality factors and dielectric anisotropy. Such characteristics enable efficient propagation of hyperbolic phonon and plasmon polaritons. Given the novelty and potential impact of this research, the findings have been published in the prestigious journal Advanced Functional Materials.
Autori:
Salvatore Macis, Annalisa D’Arco, Eugenio Del Re, Lorenzo Mosesso, Maria Chiara Paolozzi, Vincenzo Stagno, Alexander McLeod, Yu Tao, Pahuni Jain, Yi Zhang, Fred Tutt, Marco Centini, Maria Cristina Larciprete, Chris Leighton, and Stefano Lupi
This publication was supported by the European Union under the Italian National Recovery and Resilience Plan (NRRP) of Next Generation EU partnership PE0000023-NQSTI, and MUR PRIN project PHOtonics Terahertz devices based on tOpological materials (PHOTO) 2020RPEPNH. All work at the University of Minnesota (crystal growth and characterization) was supported by the US Department of Energy through the University of Minnesota (UMN) Center for Quantum Materials under DE-SC0016371. Parts of this work were conducted in the UMN Characterization Facility, which is partially supported by the US National Science Foundation through the MRSEC program under DMR-2011401. The authors acknowledge support through the PRIN 2022 MUR Project No. 20223T577Z.
Article : https://advanced.onlinelibrary.wiley.com/doi/full/10.1002/adfm.202512820