Lattice Dynamics and Electron–Phonon Coupling in Double Perovskite Cs2NaFeCl6

Autor: Bin Zhang, Johan Klarbring, Fuxiang Ji, Sergei I. Simak, Igor A. Abrikosov, Feng Gao, Galyna Yu Rudko, Weimin M. Chen, Irina A. Buyanova
Rok vydání: 2023
Předmět:
Zdroj: The Journal of Physical Chemistry C. 127:1908-1916
ISSN: 1932-7455
1932-7447
DOI: 10.1021/acs.jpcc.2c07493
Popis: Phonon-phonon and electron/exciton-phonon coupling play a vitally important role in thermal, electronic, as well as optical properties of metal halide perovskites. In this work, we evaluate phonon anharmonicity and coupling between electronic and vibrational excitations in novel double perovskite Cs2NaFeCl6 single crystals. By employing comprehensive Raman measurements combined with first-principles theoretical calculations, we identify four Raman-active vibrational modes. Polarization properties of these modes imply Fm (3) over barm symmetry of the lattice, indicative for on average an ordered distribution of Fe and Na atoms in the lattice. We further show that temperature dependence of the Raman modes, such as changes in the phonon line width and their energies, suggests high phonon anharmonicity, typical for double perovskite materials. Resonant multiphonon Raman scattering reveals the presence of high-lying band states that mediate strong electron-phonon coupling and give rise to intense nA(1g) overtones up to the fifth order. Strong electron-phonon coupling in Cs2NaFeCl6 is also concluded based on the Urbach tail analysis of the absorption coefficient and the calculated Frohlich coupling constant. Our results, therefore, suggest significant impacts of phonon-phonon and electron-phonon interactions on electronic properties of Cs2NaFeCl6, important for potential applications of this novel material. Funding Agencies|Knut and Alice Wallenberg Foundation [KAW 2019.0082]; Swedish Energy Agency [48758-1]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoeping University (Faculty Grant SFO-Mat-LiU ) [2009-00971]; Swedish Foundation for Strategic Research [UKR22-0029]; Swedish Research Council (VR) [2019-05551]; ERC (synergy grant FAST-CORR project) [854843]; Swedish Research Council [2018-05973]
Databáze: OpenAIRE
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