Direct Observation of Dipole Formation Triggered by Interlayer Sliding at Atomic Level in Semimetal MoTe<sub>2</sub>.
basic_science · Level V
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- Record sourced from PubMed, PMID 40505029.
- Also identified by DOI 10.1021/acs.nanolett.5c02590.
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Abstract
Octahedral MoTe<sub>2</sub> is a nonpolar 1T' phase and transforms into polar T<sub>d</sub> phase at ∼260 K, along with the change of the layer stacking order. However, as it is difficult to capture the interlayer sliding at atomic resolution, the polarization formation mechanism of MoTe<sub>2</sub> by cooling to low temperature remains largely unclear. Here, we address the challenge by in situ cryo-(S)TEM to trace the interlayer sliding at the atomic level and the induced polarization in vdW-layered MoTe<sub>2</sub>. When it is in the range of 300-193 K, we observed the step-by-step formation of the local T<sub>d</sub> domain within the 1T'-I domain. Moreover, we present an atomic-scale observation of the disordered mixed stacking of 1T'/T<sub>d</sub> phases at 110 K. Two possible sliding models are built with the sliding energy barriers (2.7 and 5.3 meV/u.c.), indicating thermally accessible sliding behavior. Our investigation of sliding-induced polarization provides meaningful insights for developing sliding ferroelectric-based nonvolatile memory devices.