@article{7792, abstract = {Phonon polaritons—light coupled to lattice vibrations—in polar van der Waals crystals are promising candidates for controlling the flow of energy on the nanoscale due to their strong field confinement, anisotropic propagation and ultra-long lifetime in the picosecond range1,2,3,4,5. However, the lack of tunability of their narrow and material-specific spectral range—the Reststrahlen band—severely limits their technological implementation. Here, we demonstrate that intercalation of Na atoms in the van der Waals semiconductor α-V2O5 enables a broad spectral shift of Reststrahlen bands, and that the phonon polaritons excited show ultra-low losses (lifetime of 4 ± 1 ps), similar to phonon polaritons in a non-intercalated crystal (lifetime of 6 ± 1 ps). We expect our intercalation method to be applicable to other van der Waals crystals, opening the door for the use of phonon polaritons in broad spectral bands in the mid-infrared domain.}, author = {Taboada-Gutiérrez, Javier and Álvarez-Pérez, Gonzalo and Duan, Jiahua and Ma, Weiliang and Crowley, Kyle and Prieto Gonzalez, Ivan and Bylinkin, Andrei and Autore, Marta and Volkova, Halyna and Kimura, Kenta and Kimura, Tsuyoshi and Berger, M. H. and Li, Shaojuan and Bao, Qiaoliang and Gao, Xuan P.A. and Errea, Ion and Nikitin, Alexey Y. and Hillenbrand, Rainer and Martín-Sánchez, Javier and Alonso-González, Pablo}, issn = {14764660}, journal = {Nature Materials}, pages = {964–968}, publisher = {Springer Nature}, title = {{Broad spectral tuning of ultra-low-loss polaritons in a van der Waals crystal by intercalation}}, doi = {10.1038/s41563-020-0665-0}, volume = {19}, year = {2020}, }