Anthracene-assisted inverse transport growth and superconductivity at 3.3 K in unsupported ultrathin {110} Nb and {0001} NbSe2 nanoplates

Abstract

An anthracene vapor-assisted inverse transport growth mechanism of unsupported ultrathin two-dimensional (2D) superconducting single-crystal niobium (Nb) and niobium diselenide (NbSe₂) nanoplates (thickness ∼2.5 nm) using anthracene and NbSe₂ powders as precursors is reported. Besides the whisker-like counterparts, the anthracene vapor hierarchical invasion into NbSe₂ leads to 2D Nb nanoplates with a {110} surface and 2D few-layered {0001} NbSe₂ nanoplates grown in the high-temperature residual region, while sub-millimeter selenium whiskers are found in the low-temperature transporting region. Direct magnetization measurements demonstrated that superconductivity at ∼3.3 K was clearly observed in the unsupported ultrathin Nb and NbSe₂ nanoplates. These findings may offer a new way to produce freestanding single-crystal 2D superconductors and elemental 2D metallic nanoplates.