Evidence for the weakly coupled electron mechanism in an Anderson-Blount polar metal

Abstract

Over 50 years ago, Anderson and Blount proposed that ferroelectric-like structural phase transitions may occur in metals, despite the expected screening of the Coulomb interactions that often drive polar transitions. Recently, theoretical treatments have suggested that such transitions require the itinerant electrons be decoupled from the soft transverse optical phonons responsible for polar order. However, this decoupled electron mechanism (DEM) has yet to be experimentally observed. Here we utilize ultrafast spectroscopy to uncover evidence of the DEM in LiOsO${}_3$, the first known band metal to undergo a thermally driven polar phase transition ($T_c$ =140 K). We demonstrate that intra-band photo-carriers relax by selectively coupling to only a subset of the phonon spectrum, leaving as much as 60 % of the lattice heat capacity decoupled. This decoupled heat capacity is shown to be consistent with a previously undetected and partially displacive TO polar mode, indicating the DEM in LiOsO${}_3$.

15 pages main text, 4 figures, 12 pages supplementary information

References in corpus (5)

• Ultrafast transient response and electron-phonon coupling in the iron-pnictide superconductor Ba(Fe(1-x)Co(x))2As2
• Dual nature of the ferroelectric and metallic state in LiOsO${}_3$
• Metallic ferroelectricity induced by anisotropic unscreened coulomb interaction in LiOsO3
• Raman phonons in the ferroelectric-like metal LiOsO${}_3$
• Gap-dependent quasiparticle dynamics and coherent acoustic phonons in parent iron pnictide CaFe2As2 across the spin density wave phase transition

Cited by in corpus (11)

• Polar Metals Taxonomy for Materials Classification and Discovery
• Electrical Detection of Ferroelectric-like Metals through Nonlinear Hall Effect
• Free carrier induced ferroelectricity in layered perovskites
• Spin-Phonon Resonances in Nearly Polar Metals with Spin-Orbit Coupling
• Emergent superconductivity in doped ferroelectric hafnia
• Evidence for an extended critical fluctuation region above the polar ordering transition in LiOsO${}_3$
• Phonon-Induced Collective Modes in Spin-Orbit Coupled Polar Metals
• Quantum fluctuation of ferroelectric order in polar metals
• Clues to potential dipolar-Kondo and RKKY interactions in a polar metal
• Study of polycrystalline bulk Sr${}_3$OsO${}_6$ double-perovskite insulator: comparison with 1000 K ferromagnetic epitaxial films
• A large modulation of electron-phonon coupling and an emergent superconducting dome in doped strong ferroelectrics