Study of Elastic and Structural Properties of BaFe2As2 Ultrathin Film Using Picosecond Ultrasonics
| Autor: | Di Cheng, Boqun Song, Jong-Hoon Kang, Chris Sundahl, Anthony L. Edgeton, Liang Luo, Joong-Mok Park, Yesusa G. Collantes, Eric E. Hellstrom, Martin Mootz, Ilias E. Perakis, Chang-Beom Eom, Jigang Wang |
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| Jazyk: | angličtina |
| Rok vydání: | 2023 |
| Předmět: |
ultrathin film
BaFe2As2 intrinsic strain longitudinal acoustic phonon through-thickness elastic stiffness coefficient (C33) Technology Electrical engineering. Electronics. Nuclear engineering TK1-9971 Engineering (General). Civil engineering (General) TA1-2040 Microscopy QH201-278.5 Descriptive and experimental mechanics QC120-168.85 |
| Zdroj: | Materials, Vol 16, Iss 21, p 7031 (2023) |
| Druh dokumentu: | article |
| ISSN: | 1996-1944 |
| DOI: | 10.3390/ma16217031 |
| Popis: | We obtain the through-thickness elastic stiffness coefficient (C33) in nominal 9 nm and 60 nm BaFe2As2 (Ba-122) thin films by using picosecond ultrasonics. Particularly, we reveal the increase in elastic stiffness as film thickness decreases from bulk value down to 9 nm, which we attribute to the increase in intrinsic strain near the film-substrate interface. Our density functional theory (DFT) calculations reproduce the observed acoustic oscillation frequencies well. In addition, temperature dependence of longitudinal acoustic (LA) phonon mode frequency for 9 nm Ba-122 thin film is reported. The frequency change is attributed to the change in Ba-122 orthorhombicity (a−b)/(a+b). This conclusion can be corroborated by our previous ultrafast ellipticity measurements in 9 nm Ba-122 thin film, which exhibit strong temperature dependence and indicate the structural phase transition temperature Ts. |
| Databáze: | Directory of Open Access Journals |
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