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arXiv · 1911.11921

Coupled Sublattice Melting and Charge-Order Transition in Two Dimensions

Tyler S. Smith·Fangfei Ming·Daniel González Trabada·César González·Diego Soler-Polo·Fernando Flores·José Ortega·Hanno H. Weitering
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Abstract

Two-dimensional melting is one of the most fascinating and poorly understood phase transitions in nature. Theoretical investigations often point to a two-step melting scenario involving unbinding of topological defects at two distinct temperatures. Here we report on a novel melting transition of a charge-ordered K-Sn alloy monolayer on a silicon substrate. Melting starts with short-range positional fluctuations in the K sublattice while maintaining long-range order, followed by longer-range K diffusion over small domains, and ultimately resulting in a molten sublattice. Concomitantly, the charge-order of the Sn host lattice collapses in a multi-step process with both displacive and order-disorder transition characteristics. Our combined experimental and theoretical analysis provides a rare insight into the atomistic processes of a multi-step melting transition of a two-dimensional materials system.

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Tyler S. Smith, Fangfei Ming, Daniel González Trabada, César González, Diego Soler-Polo, Fernando Flores, José Ortega, Hanno H. Weitering. 2019-11-27. Coupled Sublattice Melting and Charge-Order Transition in Two Dimensions. https://doi.org/10.1103/physrevlett.124.097602

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