High-Tc Superconductivity in Functionalized Out-of-Plane Ordered Double Transition Metal MXenes

Mohammad Keivanloo; Fateme Dinmohammad; Shashi B. Mishra; Mohammad Sandoghchi; Mohammad Javad Arshia; Mitsuaki Kawamura; Elena R. Margine; Muhammad Haris Mahyuddin; Hannes Raebiger; Reza Pamungkas Putra Sukanli; Kenta Hongo; Ryo Maezono; Mohammad Khazaei

paper

High-Tc Superconductivity in Functionalized Out-of-Plane Ordered Double Transition Metal MXenes

arXiv:2602.12960

Abstract

Two-dimensional (2D) superconductors attracted growing interest in condensed-matter physics research. In this work, we explore the superconducting properties of surface-functionalized, out-of-plane ordered double transition-metal MXenes (o-MXenes), which exhibit distinctive structural and electronic characteristics. Using first-principles calculations, we investigate the effects of electronic structure, electron-phonon coupling (EPC), anharmonicity, and anisotropy effect in superconductivity properties of o-MXenes. We examine a wide range of o-MXene systems, M $_{2}$ M $^{'}$ X $_{2}$ T $_{2}$ (M = Mo, W; M $^{'}$ = Sc, Ti, V, Mo, Zr, Nb, Ta; X = C, N), functionalized with F, O, Cl, and H groups. Out of 128 candidates, 32 compounds are found to be mechanically, dynamically, and thermodynamically stable, exhibiting superconducting transition temperatures (T $_{c}$ ) from 0.1 K to 52 K. Notably, the Mo $_{2}$ ScN $_{2}$ O $_{2}$ compound achieves the highest T $_{c}$ of 52 K, with a superconducting gap of $\sim$ 10 meV. Solving the anisotropic Eliashberg equation reveals that Mo $_{2}$ ScN $_{2}$ O $_{2}$ is an anisotropic two-gap superconductor, and incorporating anharmonic effects decreases its T $_{c}$ slightly. We further analyze flat-band-induced EPC enhancement and present EPC matrix elements as functions of phonon wavevector q for distinct vibrational modes that show anharmonic behavior of these materials.