Browsing by Author "Wu, Zefei"
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Item Giant enhanced stability of the quantum electron solid from a weakened electron-electron interaction in double-layer MoS 2(Physical Review B, 2024-03-19) Chui, S. T.; Huang, Meizhen; Wu, Zefei; Wang, NingThe melting temperature of the quantum electron solid in double-layer two-dimensional MoS2 stacked on opposite sides of a thin layer of BN is larger than previous single-layer results in Si-MOSFETs and bilayer estimates by four orders of magnitude. This giant enhancement of the stability of the solid comes from a shear modulus μ that is an order of magnitude larger than expected and comes from a weakened electron-electron interaction due to the screening by the polarization charges at the interfaces of the experimental structure. We found that the short-range part of the interelectron Coulomb potential actually provides for a negative contribution to μ and makes the lattice less stable. The weakening of this short-range contribution enhances μ by an order of magnitude. This large μ, together with a larger energy scale e2/ab for a smaller Bohr radius ab for the experimental structure, leads to a high melting temperature and makes possible using the structure as a practical logic device. Our understanding of this phenomenon guides us in optimizing its design. The large melting temperature and the small zero-temperature critical density agrees with experimental results extracted from the density and temperature dependence of the Coulomb drag resistance.Item Quantum Solid Phase and Coulomb Drag in 2D Electron–Electron Bilayers of MoS2(Advanced Electronic Materials, 2023-03-10) Huang, Meizhen; Wu, Zefei; Wang, Ning; Chui, Siu-TatCoulomb drag experiments can give information about the interaction state of double-layer systems. Here, anomalous Coulomb drag behaviors are demonstrated in a 2D electron–electron bilayer system constructed by stacking atomically thin MoS2 on opposite sides of thin dielectric layers of boron nitride. In the low-temperature regime, the measured drag resistance does not follow the behavior predicted by the Coulomb drag models of exchanging momenta and energies with the particles in Fermi-liquid bilayer systems. Instead, it shows an upturn to higher and higher values. Quantum solid/fluid phases and the Kosterlitz–Thouless/Wigner 2D quantum melting transition are investigated in this bilayer system and this interesting phenomenon is described based on thermally activated carriers of quantum defects from the formation of the correlation-induced electron solid phases, with enhanced stabilization by the potential due to the boron nitride dielectric layers.