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${}_3$ 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${}_3$ 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.

Supplementary materials on request

References in corpus (2)

• Fermi surface of the most dilute superconductor
• Ferroelectric, quantum paraelectric or paraelectric? Calculating the evolution from BaTiO${}_3$ to SrTiO${}_3$ to KTaO${}_3$ using a single-particle quantum-mechanical description of the ions

Cited by in corpus (12)

• Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites
• The phonon thermal Hall angle in black phosphorus
• Generalized Rashba Electron-Phonon Coupling and Superconductivity in Strontium Titanate
• Lamellar fluctuations melt ferroelectricity
• Phonon hydrodynamic regimes in sapphire
• Tunable Spatiotemporal Orders in Driven Insulators
• Phonon hydrodynamics in bulk insulators and semi-metals
• Beyond being free: glassy dynamics of SrTiO${}_3$-based two-dimensional electron gas
• Modeling polar order in compressively strained SrTiO${}_3$
• Electronic spin susceptibility in metallic strontium titanate
• Nanoscale Polar Landscapes in Quantum Paraelectric SrTiO3
• Effects of doping on polar order in SrTiO${}_3$ from first-principles modeling