Liu Liwei, Wang Xin, Wang Nan, Chen Yaru, Wang Shumin, Hua Caizhi, Song Tielei, Liu Zhifeng, Cui Xin
Inner Mongolia Key Laboratory of Microscale Physics and Atom Innovation, School of Physical Science and Technology, Inner Mongolia University, Hohhot 010021, China.
Nanomaterials (Basel). 2025 Jul 17;15(14):1109. doi: 10.3390/nano15141109.
Group IV element-based topological semimetals (TSMs) are pivotal for next-generation quantum devices due to their ultra-high carrier mobility and low-energy consumption. However, germanium (Ge)-based TSMs remain underexplored despite their compatibility with existing semiconductor technologies. Here, we propose a novel I229-Ge allotrope constructed via bottom-up cluster assembly that exhibits a unique porous spherical Fermi surface and strain-tunable topological robustness. First-principles calculations reveal that I229-Ge is a topological nodal line semimetal with exceptional mechanical anisotropy (Young's modulus ratio: 2.27) and ductility (/ = 2.21, = 0.30). Remarkably, the topological property persists under spin-orbit coupling (SOC) and tensile strain, while compressive strain induces a semiconductor transition (bandgap: 0.29 eV). Furthermore, I229-Ge demonstrates strong visible-light absorption (10 cm) and a strong strain-modulated infrared response, surpassing conventional Ge allotropes. These findings establish I229-Ge as a multifunctional platform for strain-engineered nanoelectronics and optoelectronic devices.
基于第IV族元素的拓扑半金属（TSMs）因其超高的载流子迁移率和低能耗，对下一代量子器件至关重要。然而，尽管基于锗（Ge）的TSMs与现有半导体技术兼容，但仍未得到充分探索。在此，我们提出一种通过自底向上的团簇组装构建的新型I229-Ge同素异形体，它具有独特的多孔球形费米面和应变可调的拓扑鲁棒性。第一性原理计算表明，I229-Ge是一种拓扑节线半金属，具有优异的机械各向异性（杨氏模量比：2.27）和延展性（/ = 2.21， = 0.30）。值得注意的是，在自旋轨道耦合（SOC）和拉伸应变下，拓扑性质依然存在，而压缩应变则会引发半导体转变（带隙：0.29 eV）。此外，I229-Ge表现出强烈的可见光吸收（10 cm）和强烈的应变调制红外响应，超过了传统的Ge同素异形体。这些发现确立了I229-Ge作为应变工程纳米电子学和光电器件的多功能平台。
