Phase Transition and Superconductivity Enhancement in Se-Substituted MoTe2 Thin Films.

Consecutively tailoring few-layer transition metal dichalcogenides MX2 from 2H to Td phase may realize the long-sought topological superconductivity in a single material system by incorporating superconductivity and the quantum spin Hall effect together. Here, this study demonstrates that a consecutive structural phase transition from Td to 1T' to 2H polytype can be realized by increasing the Se concentration in Se-substituted MoTe2 thin films. More importantly, the Se-substitution is found to dramatically enhance the superconductivity of the MoTe2 thin film, which is interpreted as the introduction of two-band superconductivity. The chemical-constituent-induced phase transition offers a new strategy to study the s+- superconductivity and the possible topological superconductivity, as well as to develop phase-sensitive devices based on MX2 materials.

Molecular Dynamics of Hexamethylbenzene at Low Temperatures: Evidence of Unconventional Magnetism Based on Rotational Motion of Protons.

The types of magnetism known to date are all mainly based on contributions from electron motion. We show how rotational motion of protons (H+ ) within the methyl groups in hexamethylbenzene (C6 (CH3 )6 ) also contribute significantly to the magnetic susceptibility. Starting from below 118 K, as the rotational motion of the methyl groups set in, an associated magnetic moment positive in nature due to charge of the protons renders the susceptibility to become anomalously dependent on temperature. Starting from 20 K, the susceptibility diverges with decreasing temperature indicative of spin-spin interactions between methyl groups aligned in a previously unclassified type of anti-ferromagnetic configuration. Complementary dielectric constant measurements also show the existence of magneto-dielectric coupling. Our findings allow for the study of strongly correlated systems that are based on a species that possesses much slower dynamics.