Emergent Ferromagnetism and Spin Gapless Conductivity in Atomically Thin Co3Sn2S2 Nanosheets

The Research group of Dr. Subhajit Roychowdhury [Department of Chemistry] developed a simple route to realize spin gapless conductivity in atomically thin Co3Sn2S2 nanosheets. Spin-gapless semiconductors (SGSs) represent an intriguing class of quantum materials that bridge the gap between half-metallic ferromagnets and conventional semiconductors, offering promising avenues for spintronic applications. The discovery of intrinsic ferromagnetism in ultrathin two-dimensional van der Waals crystals has further fueled interest in exploring magnetism at the ultimate two-dimensional limit. Here, we demonstrate the growth of environmentally stable, atomically thin Co3Sn2S2 nanosheets via a simple hydrothermal method. These nanosheets exhibit robust ferromagnetism with a Curie temperature of ~100 K and remarkably, host a spin-gapless semiconducting (SGS) state, distinct from the well-known half-metallic Weyl ferromagnetism observed in the bulk counterpart. Structural analysis reveals that enhanced lattice distortion and strain effects in the nanosheets, induced by reduced dimensionality and surface defects, play a critical role in stabilizing this phase. Williamson-Hall analysis confirms the presence of strain, while DFT calculations reveal that strain-induced lattice distortions annihilate the Weyl points and the emergence of SGS semiconductivity. Charge transport measurements indicate a Mott variable-range hopping mechanism, while temperature-dependent conductivity suggests a coexistence of semiconducting and weakly gapless features. These findings not only establish atomically thin Co3Sn2S2 nanosheets as a novel platform for SGS physics but also open exciting possibilities for strain-engineered topological phases and next-generation spintronic and quantum technologies. For more details, kindly visit: https://doi.org/10.1021/jacs.5c08223