Dual Optical Hyperbolicity of PdCoO <sub>2</sub> and PdCrO <sub>2</sub> Delafossite Single Crystals
Abstract Hyperbolic materials exhibit a very peculiar optical anisotropy with simultaneously different signs of the dielectric tensor components. This anisotropy allows the propagation of exotic surface‐wave excitations like hyperbolic phonons and plasmon polaritons. While hyperbolic materials hold promise for applications in subwavelength photonics and enhanced light‐matter interactions, their natural occurrence is limited to a few materials, often accompanied by significant dielectric losses and limited hyperbolic spectral bandwidth. Focusing on PdCoO 2 and PdCrO 2 delafossite transition‐metal oxides, in this paper unique dual hyperbolic regimes are demonstrated:: one localized around a phonon absorption in the mid‐infrared spectral region, and the other extending into the visible range. Both hyperbolic regimes show exceptional properties including low dissipation and high hyperbolic quality factors. These results pave the way for innovative applications of delafossite layered metals in subwavelength photonics, imaging, and sensing.
Authors
- S. Lupi (ORCID: https://orcid.org/0000-0001-7002-337X)
- Maria Chiara Paolozzi (ORCID: https://orcid.org/0000-0002-3714-8303)
- Salvatore Macis (ORCID: https://orcid.org/0000-0003-2360-2920)
- Fred Tutt (ORCID: https://orcid.org/0000-0002-4391-1360)
- Priyanka Jain (ORCID: https://orcid.org/0000-0003-4416-3904)
- Annalisa D’Arco (ORCID: https://orcid.org/0000-0001-7990-5117)
- Vincenzo Stagno (ORCID: https://orcid.org/0000-0002-8710-0885)
- Lorenzo Mosesso (ORCID: https://orcid.org/0000-0002-5470-8659)
- Alexander McLeod (ORCID: https://orcid.org/0000-0002-5232-634X)
- Maria Cristina Larciprete (ORCID: https://orcid.org/0000-0002-7876-628X)
- Marco Centini (ORCID: https://orcid.org/0000-0003-0625-0054)
- Chris Leighton (ORCID: https://orcid.org/0000-0003-2492-0816)
- Yi Zhang (ORCID: https://orcid.org/0009-0000-0532-7051)
- Yu Tao (ORCID: https://orcid.org/0000-0001-5997-9143)
- Eugenio Del Re
Institutions
- University of Minnesota (US)
- Sapienza University of Rome (IT)
Publication Details
- Journal
- Advanced Functional Materials
- Published
- 2025-07-14
- DOI
- https://doi.org/10.1002/adfm.202512820
- Citations
- 2
- Primary Topic
- Copper-based nanomaterials and applications
- Type
- article
- Field-Weighted Citation Impact
- 1.04
Funders
- National Science Foundation
- U.S. Department of Energy
- University of Minnesota
- European Commission
- Materials Research Science and Engineering Center, Harvard University
- Division of Materials Research