Correlated local dipoles in PbTe

Abstract

We present a combined single-crystal x-ray diffuse scattering and ab-initio molecular dynamics study of lead telluride, PbTe. Well-known for its thermoelectric and narrow-gap semiconducting properties, PbTe recently achieved further notoriety following the report of an unusual off-centering of the lead atoms, accompanied by a local symmetry breaking, on heating. This observation, which was named emphanisis, ignited considerable controversy regarding the details of the underlying local structure and the appropriate interpretation of the total scattering experiments. In this study, we demonstrate close agreement between our diffuse scattering measurements and our calculations, which allows us to analyze features such as higher-order correlations that are accessible in the simulations but not experimentally. This allowed us to discover an unusual correlated local dipole formation extending over several unit cells with an associated local reduction of the cubic symmetry in both our x-ray diffuse scattering measurements and our molecular dynamics simulations. Importantly, when averaged spatially or temporally, the most probable positions for the ions are at the centers of their coordination polyhedra. Our results therefore clarify the nature of the local symmetry breaking, and reveal the source of the earlier controversy regarding the existence or absence of off-centering. Finally, we provide an interpretation of the behavior in terms of coupled soft optical and acoustic modes, which is linked also to the high thermoelectric performance of PbTe.

arXiv commentRevision of the paper, results unchanged, improved clarity of the arguments and results

References in corpus (17)

• Canonical sampling through velocity-rescaling
• Restoring the density-gradient expansion for exchange in solids and surfaces
• Generalized gradient approximation for solids and their surfaces
• Relativistic separable dual-space Gaussian Pseudopotentials from H to Rn
• PDFgetX3: A rapid and highly automatable program for processing powder diffraction data into total scattering pair distribution functions
• First-principles theory of ferroelectric phase transitions for perovskites: The case of BaTiO3
• Giant Anharmonic Phonon Scattering in PbTe
• Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics
• Thermoelectric enhancement in PbTe with K, Na co-doping from tuning the interaction of the light and heavy hole valence bands
• First-principles accurate total-energy surfaces for polar structural distortions of BaTiO3, PbTiO3, and SrTiO3: consequences to structural transition temperatures
• Understanding the insulating phase in CMR manganites: Shortening of the Jahn-Teller long-bond across the phase diagram of La_{1-x} Ca_x Mn O_3
• Lattice dynamics reveals a local symmetry breaking in the emergent dipole phase of PbTe
• A first-principles approach to nonlinear lattice dynamics: Anomalous spectra in PbTe
• Charge density wave fluctuations, heavy electrons, and superconductivity in KNi${}_2$S${}_2$
• Origin of anomalous anharmonic lattice dynamics of lead telluride
• Fermi surface evolution of Na-doped PbTe studied through density functional theory calculations and Shubnikov-de Haas measurements
• Spectroscopic evidence for temperature-dependent convergence of light and heavy hole valence bands of PbQ (Q=Te, Se, S)

Cited by in corpus (16)

• Order-Disorder Ferroelectric Transition of Strained SrTiO3
• Expression and interactions of stereo-chemically active lone pairs and their relation to structural distortions and thermal conductivity
• Emphanitic anharmonicity in PbSe at high temperature and the anomalous electronic properties in the PbQ (Q=S, Se, Te) system
• A simple model for vacancy order and disorder in defective half-Heusler systems
• Tuneable Correlated Disorder in Alloys
• Photoinduced ultrafast transition of the local correlated structure in chalcogenide phase-change materials
• Tuneable local order in thermoelectric crystals
• On single crystal total scattering data reduction and correction protocols for analysis in direct space
• Diffuse Scattering from Correlated Electron Systems
• Dissipation-induced symmetry breaking: Emphanitic transitions in lead- and tin-containing chalcogenides and halide perovskites
• Electron-phonon coupling and superconductivity in the doped topological-crystalline insulator (Pb${}_{0.5}$Sn${}_{0.5}$)${}_{1-x}$In${}_x$Te
• Energy-lowering symmetry breaking creates a flat-band insulator in paramagnetic Nb3Cl8
• Anharmonic coherent dynamics of the soft phonon mode of a PbTe crystal
• Anharmonic coupling between electrons and TO phonons in the vicinity of ferroelectric quantum critical point
• Nanoscale structural correlations in a model cuprate superconductor
• Sb-5s lone pair dynamics and collinear magnetic ordering in Ba2FeSbSe5