Two-dimensional potassium borides with hidden kagome-like lattice: Topological semimetals, van Hove singularities, and superconductivity

Ting Han; ShuaiYu Wang; Bing Han; Yu Liu; Fengyu Li; Lei Wang

doi:10.1103/PhysRevB.107.235154

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Two-dimensional potassium borides with hidden kagome-like lattice: Topological semimetals, van Hove singularities, and superconductivity

Ting Han, ShuaiYu Wang, Bing Han, Yu Liu, Fengyu Li, Lei Wang

DOI 10.1103/PhysRevB.107.235154 · Physical Review B

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Abstract

The coexistence of nontrivial topological properties and superconductivity in a material offers the potential to achieve topological superconductivity and Majorana zero modes. However, research on ideal topological semimetals with superconductivity has been limited. In this paper, we utilize first-principles calculations to predict the existence of three two-dimensional potassium borides (K2B9, KB9, and KB18) with a hidden kagome-like lattice structure, inspired by the arrangement of the K2B9− cluster in an inverse sandwich configuration. Our findings reveal that all three materials exhibit phonon-mediated superconductivity, with transition temperatures (Tc) of 12.56, 14.46, and 10.50 K, respectively. Furthermore, K2B9 and KB18 are identified as topological nodal-line semimetals, while KB9 demonstrates the characteristics of an ideal Dirac semimetal due to the broken σh mirror symmetry and appropriate potassium content. The topological properties arise from the band inversion of the boron atom's px+py and pz orbitals within the B9 layer. Intriguingly, KB9 exhibits coexisting Dirac points and van Hove singularities near the Fermi level, which are a consequence of the hidden kagome-like lattice, thereby enhancing the superconducting transition temperature (Tc). This research not only sheds light on the pivotal role played by the orbital character of the B9 layer in the kagome-like lattice of potassium borides but also presents a strategy for achieving the coexistence of topological properties and superconductivity, thereby opening up possibilities for the realization of exotic physics.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
K2B9 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	12.56	Pressure not reported	unknown
KB9 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	14.46	Pressure not reported	unknown
KB18 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	10.5	Pressure not reported	unknown
B9 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	1.3	Pressure not reported	unknown
Bi2Se3 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Cd3As2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
WTe2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
MoTe2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
TaIrTe4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
Cu2Si Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
NaAlSi Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
MgB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
YRuB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
LuRuB2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
AlB4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
AlB6 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
TiB4 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	0.82	Pressure not reported	unknown
NbIr2B2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
TaIr2B2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown