Wasp-waisted magnetism in hydrothermally grown MoS₂ nanoflakes

Abstract

Two-dimensional semiconducting materials are emanating as a requisite group of materials for future nanoscale electronics and optoelectronics. Particularly, transition-metal dichalcogenides like molybdenum disulphide (MoS 2 ), a semiconducting inorganic counterpart of graphene have intrigued intensive interest as two-dimensional materials due to its novel functionalities. In this work, the utilization of high pressure and low temperature hydrothermal method offers a facile, versatile synthetic tool for MoS 2 nanoflakes formation without the addition of any surfactants. Our experimental results resolve the formation of hexagonal phase, well-ordered stacking of S–Mo–S layers, quantum confinement and interlayer interaction. The strong spin–orbit coupling in MoS 2 provides enthralling optical and magnetic properties. A large optical absorption in 400–700 nm region and strong luminescence provide evidence for the indirect to direct band gap transition in MoS 2 . Magnetic measurement results reveal ferromagnetism for all the MoS 2 nanoflakes and also indicate an increase in saturation magnetization with increase in duration of growth. In addition, a wasp-waisted hysteresis loop was also observed for the first time in MoS 2 nanostructures indicating multimodal population, increased grain growth and MoS 2 –MoO 3 coupling. Our findings provide important insights into the future applications of MoS 2 in high-performance nanodevices and spintronics.