Mesoscopic tunneling in strontium titanate
Abstract
Spatial correlation between atoms can generate a depletion in the energy dispersion of acoustic phonons. Two well known examples are rotons in superfluid helium and the Kohn anomaly in metals. Here we report on the observation of a large softening of the transverse acoustic mode in quantum paraelectric SrTiO by means of inelastic neutron scattering. In contrast to other known cases, this softening occurs at a tiny wave vector implying spatial correlation extending over a distance as long as 40 lattice parameters. We attribute this to the formation of mesoscopic fluctuating domains due to the coupling between local strain and quantum ferroelectric fluctuations. Thus, a hallmark of the ground state of insulating SrTiO is the emergence of hybridized optical-acoustic phonons. Mesoscopic fluctuating domains play a role in quantum tunneling, which impedes the emergence of a finite macroscopic polarisation.
Keywords
Cite
@article{arxiv.2203.15495,
title = {Mesoscopic tunneling in strontium titanate},
author = {Benoît Fauqué and Philippe Bourges and Alaska Subedi and Kamran Behnia and Benoît Baptiste and Bertrand Roessli and Tom Fennell and Stéphane Raymond and Paul Steffens},
journal= {arXiv preprint arXiv:2203.15495},
year = {2022}
}
Comments
Supplementary materials on request