Unidirectional ray polaritons in twisted asymmetric stacks

J Álvarez-Cuervo; M Obst; S Dixit; G Carini; A I F Tresguerres-Mata; C Lanza; E Terán-García; G Álvarez-Pérez; L F Álvarez-Tomillo; K Diaz-Granados; R Kowalski; A S Senerath; N S Mueller; L Herrer; J M De Teresa; S Wasserroth; J M Klopf; T Beechem; M Wolf; L M Eng; T G Folland; A Tarazaga Martín-Luengo; J Martín-Sánchez; S C Kehr; A Y Nikitin; J D Caldwell; P Alonso-González; A Paarmann

doi:10.1038/s41467-024-52750-3

Unidirectional ray polaritons in twisted asymmetric stacks

Nat Commun. 2024 Oct 19;15(1):9042. doi: 10.1038/s41467-024-52750-3.

Authors

J Álvarez-Cuervo^#^{1

2}, M Obst^#^{3

4}, S Dixit^#⁵, G Carini⁶, A I F Tresguerres-Mata^{1

2}, C Lanza^{1

2}, E Terán-García^{1

2}, G Álvarez-Pérez^{1

2

6

7}, L F Álvarez-Tomillo^{1

2}, K Diaz-Granados⁵, R Kowalski⁵, A S Senerath⁵, N S Mueller⁶, L Herrer⁸, J M De Teresa⁸, S Wasserroth⁶, J M Klopf⁹, T Beechem¹⁰, M Wolf⁶, L M Eng^{3

4}, T G Folland¹¹, A Tarazaga Martín-Luengo^{1

2}, J Martín-Sánchez^{1

2}, S C Kehr^{12

13}, A Y Nikitin^{14

15}, J D Caldwell¹⁶, P Alonso-González^{17

18}, A Paarmann¹⁹

Affiliations

¹ Department of Physics, University of Oviedo, Oviedo, Spain.
² Center of Research on Nanomaterials and Nanotechnology (CINN), CSIC-Universidad de Oviedo, El Entrego, Spain.
³ Institute of Applied Physics, TUD Dresden University of Technology, Dresden, Germany.
⁴ Würzburg-Dresden Cluster of Excellence-EXC 2147 (ct.qmat), Dresden, Germany.
⁵ Vanderbilt University, Nashville, TN, USA.
⁶ Fritz Haber Institute of the Max Planck Society, Berlin, Germany.
⁷ Center for Biomolecular Nanotechnologies, Istituto Italiano di Tecnologia, Via Barsanti 14, Arnesano, Italy.
⁸ Instituto de Nanociencia y Materiales de Aragón (INMA), CSIC-Universidad de Zaragoza, Zaragoza, Spain.
⁹ Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany.
¹⁰ Purdue University and Birck Nanotechnology Center, West Lafayette, IN, USA.
¹¹ University of Iowa, Iowa City, IA, USA.
¹² Institute of Applied Physics, TUD Dresden University of Technology, Dresden, Germany. [email protected].
¹³ Würzburg-Dresden Cluster of Excellence-EXC 2147 (ct.qmat), Dresden, Germany. [email protected].
¹⁴ Donostia International Physics Center (DIPC), Donostia-San Sebastián, Spain. [email protected].
¹⁵ IKERBASQUE, Basque Foundation for Science, Bilbao, Spain. [email protected].
¹⁶ Vanderbilt University, Nashville, TN, USA. [email protected].
¹⁷ Department of Physics, University of Oviedo, Oviedo, Spain. [email protected].
¹⁸ Center of Research on Nanomaterials and Nanotechnology (CINN), CSIC-Universidad de Oviedo, El Entrego, Spain. [email protected].
¹⁹ Fritz Haber Institute of the Max Planck Society, Berlin, Germany. [email protected].

^# Contributed equally.

PMID: 39426947
DOI: 10.1038/s41467-024-52750-3

Abstract

The vast repository of van der Waals (vdW) materials supporting polaritons offers numerous possibilities to tailor electromagnetic waves at the nanoscale. The development of twistoptics-the modulation of the optical properties by twisting stacks of vdW materials-enables directional propagation of phonon polaritons (PhPs) along a single spatial direction, known as canalization. Here we demonstrate a complementary type of directional propagation of polaritons by reporting the visualization of unidirectional ray polaritons (URPs). They arise naturally in twisted hyperbolic stacks with very different thicknesses of their constituents, demonstrated for homostructures of $α$ -MoO₃ and heterostructures of $α$ -MoO₃ and $β$ -Ga₂O₃. Importantly, their ray-like propagation, characterized by large momenta and constant phase, is tunable by both the twist angle and the illumination frequency. Apart from their fundamental importance, our findings introduce twisted asymmetric stacks as efficient platforms for nanoscale directional polariton propagation, opening the door for applications in nanoimaging, (bio)-sensing, or polaritonic thermal management.