Manipulating superconductivity of 2M WS₂ by strain

Strain engineering has been widely used to modulate the physics properties of materials as well as to enhance device performance in the last few decades. In recent years, laser shocking technique, being an effective way to induce strain, has been adopted in the field of two dimensional (2D) materials down to the monolayer limit. In this work, we report the strain effect on superconductivity of 2M WS₂ few layers. The strain was exerted on the few-layer WS₂ samples by exposing them under a nanosecond laser. The type and magnitude of the strain are characterized by Raman spectroscopy. The electrical transport properties of the 2M WS₂ samples before and after straining were systematically characterized using electrical transport measurements. We observed a drastic change of the corresponding transport properties of the strained WS₂ samples compared with the unstrained ones. For example, the critical temperature and field of a 15 nm thick WS₂ device without applying strain were 8.42 K and 2.79 T. But for an 18 nm thick 2M WS₂ device after straining these two values decrease down to 7.8 K and 2.79 T, respectively. Correspondingly, the strain effect on the pairing symmetry of superconducting WS₂ will also be revealed. Therefore, our work may shed light on understanding and manipulating the unconventional superconductivity in low-dimensional systems.