Direct measurement of ferroelectric polarization in a tunable semimetal

Abstract

Ferroelectricity, the electrostatic counterpart to ferromagnetism, has long been thought to be incompatible with metallicity due to screening of electric dipoles and external electric fields by itinerant charges. Recent measurements, however, demonstrated signatures of ferroelectric switching in the electrical conductance of bilayers and trilayers of WTe${}_2$, a semimetallic transition metal dichalcogenide with broken inversion symmetry. An especially promising aspect of this system is that the density of electrons and holes can be continuously tuned by an external gate voltage. This degree of freedom enables investigation of the interplay between ferroelectricity and free carriers, a previously unexplored regime. Here, we employ capacitive sensing in dual-gated mesoscopic devices of bilayer WTe${}_2$ to directly measure the spontaneous polarization in the metallic state and quantify the effect of free carriers on the polarization in the conduction and valence bands, separately. We compare our results to a low-energy model for the electronic bands and identify the layer-polarized states that contribute to transport and polarization simultaneously. Bilayer WTe${}_2$ is thus shown to be a canonical example of a ferroelectric metal and an ideal platform for exploring polar ordering, ferroelectric transitions, and applications in the presence of free carriers.

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• Prediction of a native ferroelectric metal
• Capacitance of Graphene Bilayer as a Which-Layer Probe
• Direct Observation of Long-range field-effect from gate tuning of non-local conductivity

Cited by in corpus (19)

• Interfacial ferroelectricity in rhombohedral-stacked bilayer transition metal dichalcogenides
• Interfacial ferroelectricity in marginally twisted 2D semiconductors
• Coupled Ferroelectricity and Superconductivity in Bilayer $T_d$-MoTe${}_2$
• Cumulative Polarization Coexisting with Conductivity at Interfacial Ferroelectrics
• Orbital Multiferroicity in Pentalayer Rhombohedral Graphene
• Atypical sliding and Moire ferroelectricity in pure multilayer graphene
• Across-Layer Sliding Ferroelectricity in Graphene-Based Heterolayers: Asymmetry of Next Neighbor Interlayer Couplings
• Switchable and unswitchable bulk photovoltaic effect in two-dimensional interlayer-sliding ferroelectrics
• Mixed-Stacking Few-Layer Graphene as an Elemental Weak Ferroelectric Material
• Ferroelectric metals in 1T/1T'-phase transition metal dichalcogenide MTe2 bilayers (M = Pt, Pd, and Ni)
• Unveiling the origin of unconventional moire ferroelectricity
• Ferroelectric control of charge-to-spin conversion in WTe${}_2$
• Switching ferroelectricity in SnSe across diffusionless martensitic phase transition
• Ferroelectric topological superconductor
• Quantum-Geometric Origin of Out-of-plane Stacking Ferroelectricity
• Resonant tunneling in graphene-ferroelectric-graphene junctions
• Ferroelectric response to interlayer shifting and rotations in trilayer hexagonal Boron Nitride
• Stabilization of sliding ferroelectricity through exciton condensation
• Superconducting cavity probes sliding ferroelectricity in small-angle twisted WSe${}_2$