首页|Topological and superconducting properties of monolayered CoN and CoP:A first-principles comparative study

Topological and superconducting properties of monolayered CoN and CoP:A first-principles comparative study

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Two-dimensional systems that simultaneously harbor superconductivity and nontrivial band topology may serve as appealing platforms for realizing topological superconductivity with promising applications in fault-tolerant quantum computing.Here,based on first-principles calculations,we show that monolayered CoN and CoP with the isovalent FeSe-like structure are stable in freestanding form,even though their known bulk phases have no resemblance to layering.The two systems are further revealed to display intrinsic band inversions due to crystal field splitting,and such orderings are preserved with the inclusion of spin-orbit coupling(SOC),which otherwise is able to open a curved band gap,yielding a non-zero Z2 topological invariant in each case.Such a mechanism of topologicalization is distinctly contrasted with that identified recently for the closely related monolayers of CoX(X=As,Sb,Bi),where the SOC plays an indispensable role in causing a nontrivial band inversion.Next,we demonstrate that,by applying equi-biaxial tensile strain,the electron-phonon coupling strength in monolayered CoN can be significantly enhanced,yielding a superconducting transition temperature(Tc)up to 7-12 K for the Coulomb pseudopotential ofμ=0.2-0.1,while the CoP monolayer shows very low Tc even under pronounced strain.Their different superconducting behaviors can be attributed to different variations in lattice softening and electronic density of states around the Fermi level upon pressuring.Our central findings enrich the understanding of different mechanisms of band inversions and topologicalization and offer platforms for achieving the coexistence of superconductivity and nontrivial band topology based on two-dimensional systems.

band topologysuperconductivity2D materialsfirst-principles approaches

Jiaqing Gao、Zhenyu Zhang、Ping Cui

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International Center for Quantum Design of Functional Materials(ICQD),Hefei National Research Center for Physical Sciences at Microscale(HFNL),University of Science and Technology of China,Hefei 230026,China

Hefei National Laboratory,University of Science and Technology of China,Hefei 230088,China

Innovation Program for Quantum Science and TechnologyNational Natural Science Foundation of ChinaNational Natural Science Foundation of ChinaAnhui Initiative in Quantum Information TechnologiesStrategic Priority Research Program of Chinese Academy of SciencesAnhui Provincial Key Research and Development Project

2021ZD03028001197432312374458AHY170000XDB05102002023z04020008

2024

10.1007/s11433-023-2324-0

中国科学:物理学 力学 天文学(英文版)
中国科学院

中国科学:物理学 力学 天文学(英文版)

CSTPCD
影响因子：0.91
ISSN：1674-7348
年,卷(期)：2024.67(5)