High-temperature superconductivity in two-dimensional hydrogenated titanium diboride: Ti2B2H4. (January 2023)

• Record Type: Journal Article
• Authors: Han, Yu-Lin; Li, Ya-Ping; Yang, Liu; Liu, Hao-Dong; Jiao, Na; Wang, Bao-Tian; Lu, Hong-Yan; Zhang, Ping
• Is Part Of: Materials today physics. Volume 30(2023)
• Publication Date: 2023-01
• Subjects: Materials science -- Periodicals; Physics -- Periodicals; Electronic journals; 530.41
• DOI: 10.1016/j.mtphys.2022.100954
• Languages: English
• ISSNs: 2542-5293

Abstract

Abstract: In recent years, superconductivity in two-dimensional (2D) layered hexagonal metal borides has aroused much interests. Here, based on first-principles calculations, we theoretically report a new type of 2D hydrogenated transition-metal diboride: Ti2 B2 H4 . Results reveal that the introduction of hydrogen atoms expands the frequency range of phonon spectrum of monolayer Ti2 B2, and significantly increases the electron-phonon coupling (EPC). The calculated EPC constant λ of Ti2 B2 H4 is 1.18, and the corresponding superconducting critical temperature ( T c ) is 48.6 K, exceeding the McMillan limit (39 K). The EPC mainly originates from the coupling between electrons in Ti-3 d orbitals and the low-frequency vibration modes of Ti atoms as well as high-frequency vibration modes of H atoms. Additionally, the coupling strength can be further increased to 1.61 by applying appropriate biaxial compressive strain, and the corresponding T c can be boosted to 69.4 K, approaching to liquid nitrogen (N2 ) temperature. The predicted Ti2 B2 H4 provides a new platform for 2D superconductivity and may have potential applications in 2D nanodevices. Graphical abstract: Hydrogenated monolayer Ti2B2, i.e., Ti2B2H4, is a phonon-mediated superconductor with Tc of 48.6 K. By applying appropriate biaxial compressive strain, the Tc can be boosted to 69.4 K, approaching to liquid nitrogen temperature. Image 1 Highlights: Ti2 B2 H4 is a phonon-mediated superconductor with Tc of 48.6 K, exceeding the McMillan limit. Superconductivity in Ti2 B2 H4 originates from the coupling between Ti 3 d -electrons and the vibration modes of Ti and H atoms. By applying biaxial compressive strain of -9%, the Tc of Ti2 B2 H4 can be boosted to 69.4 K.