Journal article
Spectral Tuning of Hyperbolic Shear Polaritons in Monoclinic Gallium Oxide via Isotopic Substitution
Advanced materials (Weinheim), Vol.38(11), e14561
02/2026
DOI: 10.1002/adma.202514561
PMCID: PMC12921354
PMID: 41518292
Abstract
Hyperbolic phonon polaritons ‐ hybridized modes arising from the ultrastrong coupling of infrared light to strongly anisotropic lattice vibrations in uniaxial or biaxial polar crystals ‐ enable to confine light to the nanoscale with low losses and high directionality. In even lower symmetry materials, such as monoclinic ‐Ga 2 O 3 (bGO), hyperbolic shear polaritons (HShPs) further enhance the directionality. Yet, HShPs are intrinsically supported only within narrow frequency ranges defined by the phonon frequencies of the host material. Here, we report spectral tuning of HShPs in bGO by isotopic substitution. Employing near‐field optical microscopy to image HShPs in 18 O bGO films homoepitaxially grown on a 16 O bGO substrate, we demonstrate a spectral redshift of 40 cm −1 for the 18 O bGO, compared to 16 O bGO. The technique allows for direct observation and a model‐free estimation of the spectral shift driven by isotopic substitution without the need for knowledge of the dielectric tensor. Complementary far‐field measurements and ab initio calculations ‐ in good agreement with the near‐field data ‐ confirm the effectiveness of this estimation. This multifaceted study demonstrates a significant isotopic substitution induced spectral tuning of HShPs into a previously inaccessible frequency range, creating new avenues for technological applications of such highly directional polaritons.
Details
- Title: Subtitle
- Spectral Tuning of Hyperbolic Shear Polaritons in Monoclinic Gallium Oxide via Isotopic Substitution
- Creators
- Giulia Carini - Fritz Haber Institute of the Max Planck SocietyMohit Pradhan - University of IowaElena Gelžinytė - Fritz Haber Institute of the Max Planck SocietyAndrea Ardenghi - Forschungsverbund BerlinSaurabh Dixit - Vanderbilt UniversityMaximilian Obst - Technische Universität DresdenAditha S. Senarath - Vanderbilt UniversityNiclas S. Mueller - Fritz Haber Institute of the Max Planck SocietyGonzalo Álvarez-Pérez - Center for Biomolecular NanotechnologiesKatja Diaz-Granados - Vanderbilt UniversityRyan A. Kowalski - Vanderbilt UniversityRicharda Niemann - Fritz Haber Institute of the Max Planck SocietyFelix G. Kaps - Technische Universität DresdenJakob Wetzel - Technische Universität DresdenRaghunandan Balasubramanyam Iyer - University of Iowa, Physics and AstronomyPiero Mazzolini - University of ParmaMathias Schubert - University of Nebraska–LincolnJ. Michael Klopf - Helmholtz-Zentrum Dresden-RossendorfJohannes T. Margraf - University of BayreuthOliver Bierwagen - Forschungsverbund BerlinMartin Wolf - Fritz Haber Institute of the Max Planck SocietyKarsten Reuter - Fritz Haber Institute of the Max Planck SocietyLukas M. Eng - Technische Universität DresdenSusanne C. Kehr - Technische Universität DresdenJoshua D. Caldwell - Vanderbilt UniversityChristian Carbogno - Fritz Haber Institute of the Max Planck SocietyThomas G. Folland - University of IowaMarkus R. Wagner - Forschungsverbund BerlinAlexander Paarmann - Fritz Haber Institute of the Max Planck Society
- Resource Type
- Journal article
- Publication Details
- Advanced materials (Weinheim), Vol.38(11), e14561
- DOI
- 10.1002/adma.202514561
- PMID
- 41518292
- PMCID
- PMC12921354
- NLM abbreviation
- Adv Mater
- ISSN
- 0935-9648
- eISSN
- 1521-4095
- Publisher
- Wiley
- Grant note
- Deutsche Forschungsgemeinschaft (DFG, German Research Foundation): 446185170, 551280726 Alexander von Humboldt foundationBundesministerium fur Bildung und Forschung (BMBF, Federal Ministry of Education and Research, Germany): 05K19ODA, 05K19ODB, 05K22ODA Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence StrategyWurzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter-ct.qmat: EXC 2147, 390858490 Collaborative Research Center on Chemistry of Synthetic Two-Dimensional Materials: CRC1415, 417590517 Department of Energy - Basic Energy Sciences: DE-FG02-09ER4655 NASA Space Technology Graduate Research OpportunityOffice of Naval Research MURI on Twist-Optics: N0001-23-1-2567 US National Science Foundation: 2236807 Office of Naval Research: N00014-23-1-2616 NSF: ECCS 2329940, OIA-2044049 AFOSR: FA9550-25-1-0196 Knut and Alice Wallenberg Foundation: 2024.0121 Wallenberg Initiative Materials Science for Sustainability (WISE)Projekt DEAL
MBE growth was performed in the framework of GraFOx, a Leibniz-ScienceCampus, and was funded by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)-Project No. 446185170. Nicole Volkmer is gratefully acknowledged for fabrication of the Au disc launchers. E.G. thanks the Alexander von Humboldt foundation for research fellowship funding. Parts of this research were carried out at the ELBE Center for High-Power Radiation Sources at the Helmholtz-Zentrum Dresden-Rossendorf e.V., a member of the Helmholtz Association. M.O., F.G.K., J.W., L.M.E., and S.C.K. acknowledge the financial support by the Bundesministerium fur Bildung und Forschung (BMBF, Federal Ministry of Education and Research, Germany, Project Grant Nos. 05K19ODA, 05K19ODB and 05K22ODA) and by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany's Excellence Strategy through Wurzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter-ct.qmat (EXC 2147, project-id 390858490) and through the Collaborative Research Center on Chemistry of Synthetic Two-Dimensional Materials-CRC1415 (ID: 417590517). K.D.-G. was supported by the Department of Energy - Basic Energy Sciences under Grant number DE-FG02-09ER4655, while R.A.K acknowledges that this work was supported by a NASA Space Technology Graduate Research Opportunity. J.D.C., S.D., and R.B.I. were supported by the Office of Naval Research MURI on Twist-Optics under grant N0001-23-1-2567. T.G.F. and M.P. were supported by the US National Science Foundation grant 2236807. T.G.F. was also partially supported through the Office of Naval Research grant N00014-23-1-2616. M.S. acknowledges support under NSF ECCS 2329940, OIA-2044049, AFOSR FA9550-25-1-0196, Knut and Alice Wallenberg Foundation grant 2024.0121 'Transforming ceramics into next generation semiconductors', and the Wallenberg Initiative Materials Science for Sustainability (WISE). N.S.M. acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Projektnummer 551280726. Open access funding enabled and organized by Projekt DEAL.
- Language
- English
- Electronic publication date
- 01/10/2026
- Date published
- 02/2026
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9985121593402771
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