Wang Mengjing, Kumar Aakash, Dong Hao, Woods John M, Pondick Joshua V, Xu Shiyu, Hynek David J, Guo Peijun, Qiu Diana Y, Cha Judy J
Department of Mechanical Engineering and Materials Science, Yale University, New Haven, CT, 06511, USA.
Energy Sciences Institute, Yale West Campus, West Haven, CT, 06516, USA.
Adv Mater. 2022 Jun;34(24):e2200861. doi: 10.1002/adma.202200861. Epub 2022 May 12.
The Weyl semimetal WTe has shown several correlated electronic behaviors, such as the quantum spin Hall effect, superconductivity, ferroelectricity, and a possible exciton insulator state, all of which can be tuned by various physical and chemical approaches. Here, a new electronic phase in WTe induced by lithium intercalation is discovered. The new phase exhibits an increasing resistivity with decreasing temperature and its carrier density is almost two orders of magnitude lower than the carrier density of the semimetallic T phase, probed by in situ Hall measurements as a function of lithium intercalation. The theoretical calculations predict the new lithiated phase to be a potential charge density wave (CDW) phase with a bandgap of ≈0.14 eV, in good agreement with the in situ transport data. The new phase is structurally distinct from the initial T phase, characterized by polarization-angle-dependent Raman spectroscopy, and large lattice distortions close to 6% are predicted in the new phase. This finding of a new gapped phase in a 2D semimetal demonstrates electrochemical intercalation as a powerful tuning knob for modulating electron density and phase stability in 2D materials.
外尔半金属WTe展现出了多种关联电子行为，如量子自旋霍尔效应、超导性、铁电性以及可能的激子绝缘体状态，所有这些都可以通过各种物理和化学方法进行调控。在此，发现了锂嵌入诱导的WTe中的一种新电子相。该新相表现出电阻率随温度降低而增加的特性，并且通过原位霍尔测量作为锂嵌入量的函数发现，其载流子密度比半金属T相的载流子密度低近两个数量级。理论计算预测新的锂化相是一种潜在的电荷密度波（CDW）相，带隙约为0.14电子伏特，与原位输运数据吻合良好。新相与初始T相在结构上不同，通过偏振角相关拉曼光谱表征，并且预测新相中存在接近6%的大晶格畸变。在二维半金属中发现这种新的带隙相证明了电化学嵌入作为一种强大的调节旋钮，可用于调制二维材料中的电子密度和相稳定性。
