Tailoring Phonon‐Driven Responses in α‐MoO <sub>3</sub> through Isotopic Enrichment
Abstract
ABSTRACT The implementation of polaritonic materials into nanoscale devices requires selective tuning of parameters to realize desired spectral or thermal responses. One robust material, α‐MoO 3 , an orthorhombic crystal boasting three distinct phonon dispersions, provides three polaritonic dispersions of hyperbolic phonon polaritons (HPhPs) across the mid‐infrared (MIR). Here, the tunability of both optical and thermal responses in isotopically enriched α‐MoO 3 ( 98 MoO 3, Mo 18 O 3 , and 98 Mo 18 O 3 ) is explored. A uniform ∼5% spectral redshift from 18 O enrichment is observed in both Raman‐ and IR‐active TO phonons. Both the in‐ and out‐of‐plane thermal conductivities for the isotopic variations are reported. Ab initio calculations both replicate experimental findings and analyze the select‐mode three‐phonon scattering contributions. The HPhPs from each isotopic variation are probed with s‐SNOM, and we report an HPhP Q ‐factor maxima increase in 98 Mo 18 O 3 of ∼50% along the [100] in the RB 2 and ∼100% along the [001] in the RB 3 with respect to 98 MoO 3 . Observations in both real and Fourier space of higher‐order HPhP modes propagating in slabs of isotopically enriched α‐MoO 3 without the use of a subdiffractional surface scatterer are presented here. This work establishes the dual‐element isotope enrichment of α‐MoO 3 as an intrinsic strategy to design optical, thermal, and polaritonic properties.
Article Details
Authors (32)
Thiago S. Arnaud
Interdisciplinary Material Science Vanderbilt University Nashville Tennessee USA
Ryan W. Spangler
Department of Materials Science and Engineering The Pennsylvania State University University Park Pennsylvania USA
Johnathan D. Georgaras
Jonah B. Haber
Department of Materials Science and Engineering Stanford University Stanford California USA
Daniel Hirt
Department of Mechanical and Aerospace Engineering, University of Virginia 2 , Charlottesville, Virginia 22904,
Maximilian Obst
Interdisciplinary Material Science Vanderbilt University Nashville Tennessee USA
Gonzalo Álvarez‐Pérez
Istituto Italiano di Tecnologia Center for Biomolecular Nanotechnologies Lecce Italy
Mackey Long III
Interdisciplinary Material Science Vanderbilt University Nashville Tennessee USA
Felix G. Kaps
Institute of Applied Physics TUD Dresden University of Technology Dresden Germany
Jakob Wetzel
Institute of Applied Physics TUD Dresden University of Technology Dresden Germany
Courtney Ragle
Interdisciplinary Material Science Vanderbilt University Nashville Tennessee USA
John E. Buchner
Interdisciplinary Material Science Vanderbilt University Nashville Tennessee USA
Youngji Kim
Department of Mechanical Engineering Vanderbilt University Nashville Tennessee USA
Aditha S. Senarath
Interdisciplinary Material Science Vanderbilt University Nashville Tennessee USA
Richarda Niemann
Department of Mechanical Engineering Vanderbilt University Nashville Tennessee USA
Mingze He
Giulia Carini
Department of Physcial Chemistry Fritz Haber Institute of the Max Planck Society Berlin Germany
Unai Arregui‐Leon
Department of Physcial Chemistry Fritz Haber Institute of the Max Planck Society Berlin Germany
Akash C. Behera
Department of Physcial Chemistry Fritz Haber Institute of the Max Planck Society Berlin Germany
Ramachandra Bangari
Department of Physics and Astronomy University of Iowa Iowa City Iowa USA
Nihar Sahoo
Department of Physics and Astronomy University of Iowa Iowa City Iowa USA
Niels C. Brumby
Department of Physcial Chemistry Fritz Haber Institute of the Max Planck Society Berlin Germany
J. Michael Klopf
Institute of Radiation Physics Helmholtz‐Zentrum Dresden‐Rossendorf Dresden Germany
Martin Wolf
Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, Berlin 14195, Germany
Lukas M. Eng
Susanne C. Kehr
Institute of Applied Physics TUD Dresden University of Technology Dresden Germany
Thomas G. Folland
Department of Physics and Astronomy, The University of Iowa 1 , Iowa City, Iowa 52245,
Alexander Paarmann
Department of Physcial Chemistry Fritz Haber Institute of the Max Planck Society Berlin Germany
Patrick E. Hopkins
Felipe Jornada
Department of Materials Science and Engineering Stanford University Stanford California USA
Jon‐Paul Maria
Department of Materials Science and Engineering The Pennsylvania State University University Park Pennsylvania USA
Joshua D. Caldwell
Department of Mechanical Engineering Vanderbilt University Nashville Tennessee USA