Novel structures of two-dimensional tungsten boride and their superconductivity. Issue 28 (1st July 2019)

• Record Type: Journal Article
• Authors: Yan, Luo; Bo, Tao; Zhang, Wenxue; Liu, Peng-Fei; Lu, Zhansheng; Xiao, Yong-Guang; Tang, Ming-Hua; Wang, Bao-Tian
• Is Part Of: Physical chemistry chemical physics. Volume 21:Issue 28(2019)
• Page Start: 15327
• Page End: 15338
• Publication Date: 2019-07-01
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c9cp02727k
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : We predict four new tungsten boride monolayers and demonstrate that two of them are phonon-mediated superconductors with superconducting transition temperatures of 7.8 and 1.5 K. Abstract : Two-dimensional (2D) superconductors, which can be widely applied in optoelectronic and microelectronic devices, have gained renewed attention in recent years. Based on the crystal structure prediction method and first-principles calculations, we obtain four novel 2D tungsten boride structures of tetr-, hex-, and tri-W2 B2 and hex-WB4 and investigate their bonding types, electronic properties, phonon dispersions and electron–phonon coupling (EPC). The results show that both tetr- and hex-W2 B2 are intrinsic phonon-mediated superconductors with a superconducting transition temperature ( T c ) of 7.8 and 1.5 K, respectively, while tri-W2 B2 and hex-WB4 are normal metals. We demonstrate that carrier doping as well as biaxial strain can soften the low-frequency phonon modes and enhance the strength of the EPC. While the T c of tetr-W2 B2 can be increased to 15.4 K under a compressive strain of −2%, the T c of hex-W2 B2 can be enhanced to 5.9 K by a tensile strain of +4%. With the inclusion of spin–orbit couping (SOC), the value of T c decreases by 38.5% in our systems. Furthermore, we explore the stabilities and mechanical properties of tetr- and hex-W2 B2 and indicate that they may be prepared by growing on ZnS(100) and ZnS(111), respectively. Our findings provide novel 2D superconducting materials and will stimulate more efforts in this filed.