AI 中文总结
该研究针对Janus MXene TiM''CO₂（M''=Mo、W），计算发现二者因过渡金属元素不同呈现迥异量子特性，凸显MXene可作为定制多功能量子现象的平台。
AI 中文摘要
受具有Janus金属位点的双金属MXene化合物发现的推动，我们研究了Janus MXene TiM''CO₂，其中M''为Mo、W。我们的计算分析表明，Janus结构中的反演对称性破缺，加上M''处的强自旋轨道耦合，会产生多种显著的功能，包括显著的Rashba自旋分裂、非平凡的Z₂拓扑、由Berry曲率偶极子驱动的非线性反常霍尔效应，以及Berry曲率偶极子的应变调控。值得注意的是，来自元素周期表同一列的M''元素，基于4d过渡金属的TiMoCO₂和基于5d过渡金属的TiWCO₂表现出明显不同的行为：TiMoCO₂是Z₂拓扑绝缘体，而TiWCO₂是平凡半金属；不过两种化合物均展现出引人注目的量子特性。TiWCO₂具有强Rashba效应，其Rashba系数达1.35 eV·埃，非线性反常霍尔电导率达120×0.0001 G₀；TiMoCO₂是Z₂窄带隙半导体，具有较弱的Rashba分裂和中等的非线性反常霍尔电导率，且表现出应变驱动的从半导体到半金属的转变，该转变会调控Berry曲率偶极子的符号和大小，在2%的拉伸应变下可产生17×0.0001 G₀的可观非线性反常霍尔电导率。我们的研究结果凸显了MXene作为研究和定制多功能量子现象平台的潜力。
英文摘要
Motivated by the discovery of bimetallic MXene compounds with Janus metal sites, we investigate Janus MXenes TiM"CO2, where M" = Mo, W. Our computational analysis reveals that broken inversion symmetry in the Janus structure, coupled with strong spin-orbit coupling at M", generates diverse and remarkable functionalities. These include pronounced Rashba spin splitting, non-trivial Z2 topology, Berry-curvature-dipole-driven nonlinear anomalous Hall effect, and strain control of the Berry curvature dipole. Notably, the 4d transition-metal-based TiMoCO2 and 5d transition-metal-based TiWCO2, with M" elements from the same column of the periodic table, display markedly different behaviors. While TiMoCO2 is a Z2 topological insulator, TiWCO2 is a trivial semimetal. Both compounds, however, exhibit compelling quantum properties. TiWCO2 shows a robust Rashba effect with a large Rashba coefficient of 1.35 eV. Angstrom and a large nonlinear anomalous Hall conductivity of 120 x 0.0001 G0. TiMoCO2, a Z2 narrow-gap semiconductor with weaker Rashba splitting and moderate nonlinear anomalous Hall conductivity, exhibits a strain-driven transition from semiconductor to semimetal. This transition modulates both the sign and magnitude of the Berry curvature dipole, yielding a sizable nonlinear anomalous Hall conductivity of 17 X 0.0001 G0 under 2% tensile strain. Our findings underscore the potential of MXenes as a platform for investigating and tailoring multifunctional quantum phenomena.
Comments10 pages, 7 figures
