Two-Dimensional Anti-Van't Hoff/Le Bel Array AlB6 with High Stability, Unique Motif, Triple Dirac Cones, and Superconductivity

Bingyi Song; Yuan Zhou; Hui-Min Yang; Ji-Hai Liao; Li-Ming Yang; Xiao-Bao Yang; Eric Ganz

doi:10.1021/jacs.8b13075

Two-Dimensional Anti-Van't Hoff/Le Bel Array AlB₆ with High Stability, Unique Motif, Triple Dirac Cones, and Superconductivity

J Am Chem Soc. 2019 Feb 27;141(8):3630-3640. doi: 10.1021/jacs.8b13075. Epub 2019 Feb 14.

Authors

Bingyi Song¹, Yuan Zhou¹, Hui-Min Yang¹, Ji-Hai Liao², Li-Ming Yang¹, Xiao-Bao Yang², Eric Ganz³

Affiliations

¹ Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica; Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education; Hubei Key Laboratory of Materials Chemistry and Service Failure; School of Chemistry and Chemical Engineering , Huazhong University of Science and Technology , Wuhan 430074 , China.
² Department of Physics , South China University of Technology , Guangzhou 510640 , China.
³ School of Physics and Astronomy , University of Minnesota , 116 Church Street SE , Minneapolis , Minnesota 55455 , United States.

PMID: 30693774
DOI: 10.1021/jacs.8b13075

Abstract

We report the discovery of a rule-breaking two-dimensional aluminum boride (AlB₆-ptAl-array) nanosheet with a planar tetracoordinate aluminum (ptAl) array in a tetragonal lattice by comprehensive crystal structure search, first-principles calculations, and molecular dynamics simulations. It is a brand new 2D material with a unique motif, high stability, and exotic properties. These anti-van't Hoff/Le Bel ptAl-arrays are arranged in a highly ordered way and connected by two sheets of boron rhomboidal strips above and below the array. The regular alignment and strong bonding between the constituents of this material lead to very strong mechanical strength (in-plane Young's modulus Y _x = 379, Y _y = 437 N/m, much larger than that of graphene, Y = 340 N/m) and high thermal stability (the framework survived simulated annealing at 2080 K for 10 ps). Additionally, electronic structure calculations indicate that it is a rare new material with triple Dirac cones, Dirac-like fermions, and node-loop features. Remarkably, this material is predicted to be a 2D phonon-mediated superconductor with T_c = 4.7 K, higher than the boiling point of liquid helium (4.2 K). Surprisingly, the T_c can be greatly enhanced up to 30 K by applying tensile strain at 12%. This is much higher than the temperature of liquid hydrogen (20.3 K). These outstanding properties may pave the way for potential applications of an AlB₆-ptAl-array in nanoelectronics and nanomechanics. This work opens up a new branch of two-dimensional aluminum boride materials for exploration. The present study also opens a field of two-dimensional arrays of anti-van't Hoff/Le Bel motifs for study.