Emergent interface vibrational structure of oxide superlattices
- Univ. of Virginia, Charlottesville, VA (United States)
- Vanderbilt Univ., Nashville, TN (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Univ. of California, Berkeley, CA (United States)
- Pennsylvania State Univ., University Park, PA (United States)
- Paul Drude Inst. für Festkörperelektronik, Berlin (Germany); Humboldt Univ. of Berlin (Germany). Inst. for Physics
- Univ. of Southern California, Los Angeles, CA (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Center for Integrated Nanotechnologies (CINT); Purdue Univ., West Lafayette, IN (United States). Birck Nanotechnology Center
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
As the length scales of materials decrease, the heterogeneities associated with interfaces become almost as important as the surrounding materials. This has led to extensive studies of emergent electronic and magnetic interface properties in superlattices. However, the interfacial vibrations that affect the phonon-mediated properties, such as thermal conductivity, are measured using macroscopic techniques that lack spatial resolution. Although it is accepted that intrinsic phonons change near boundaries, the physical mechanisms and length scales through which interfacial effects influence materials remain unclear. Here we demonstrate the localized vibrational response of interfaces in strontium titanate–calcium titanate superlattices by combining advanced scanning transmission electron microscopy imaging and spectroscopy, density functional theory calculations and ultrafast optical spectroscopy. Structurally diffuse interfaces that bridge the bounding materials are observed and this local structure creates phonon modes that determine the global response of the superlattice once the spacing of the interfaces approaches the phonon spatial extent. Our results provide direct visualization of the progression of the local atomic structure and interface vibrations as they come to determine the vibrational response of an entire superlattice. Direct observation of such local atomic and vibrational phenomena demonstrates that their spatial extent needs to be quantified to understand macroscopic behaviour. Tailoring interfaces, and knowing their local vibrational response, provides a means of pursuing designer solids with emergent infrared and thermal responses.
- Research Organization:
- Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA); US Office of Naval Research (ONR); US Army Research Office (ARO); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division
- Grant/Contract Number:
- NA0003525; AC05-00OR22725; AC02-05CH11231; FG02-09ER46554
- OSTI ID:
- 1845384
- Alternate ID(s):
- OSTI ID: 1885374
- Report Number(s):
- SAND2022-1193J; 703200
- Journal Information:
- Nature (London), Journal Name: Nature (London) Journal Issue: 7894 Vol. 601; ISSN 0028-0836
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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