Li Longlong, Fyta Maria
Computational Biotechnology, RWTH Aachen University Worringerweg 3 52074 Aachen Germany
RSC Adv. 2025 Sep 8;15(39):32470-32476. doi: 10.1039/d5ra04294a. eCollection 2025 Sep 5.
Recent advances in two-dimensional (2D) magnetic materials have promoted significant progress in low-dimensional magnetism and its technological applications. Among them, atomically thin chromium trihalides (CrX with X = Cl, Br, and I) are among the most studied 2D magnets due to their unique magnetic properties. In this work, we employ density functional theory calculations to investigate the mechanical and electronic properties of CrX monolayers in the presence of in-plane uniaxial strain. We calculate the strain-dependent energetics, stress-strain relationships, electron localization functions, and electronic density of states for two distinct strain directions: zigzag and armchair. Our results show that the ferromagnetic phase remains the magnetic ground state over a wide range of strain in both zigzag and armchair directions. The mechanical response exhibits a distinct anisotropy between these two directions, as reflected by the maximum value in the stress-strain relationship. As the halogen atom X becomes heavier, the maximum stress decreases from 6.04 (6.40) GPa to 3.20 (3.33) GPa in the zigzag (armchair) direction. By analyzing the electron localization function, we show the strain-induced variations in bonding characteristics and their impact on the mechanical strength of the materials. We also observe a strain-induced energy splitting of the Cr-d and X-p orbitals in the electronic density of states, and a strain-induced band-gap transition (from indirect to direct) in the electronic band structure, leading to a reduction of the electronic band gap with a directional dependence on the applied strain. Our results provide fundamental insights into the effects of uniaxial strain on the mechanical and electronic properties of CrX monolayers, which are relevant for their potential use in strain-engineered electronics and spintronics.
二维（2D）磁性材料的最新进展推动了低维磁性及其技术应用的重大进步。其中，原子级薄的三卤化铬（CrX，X = Cl、Br和I）因其独特的磁性而成为研究最多的二维磁体之一。在这项工作中，我们采用密度泛函理论计算来研究面内单轴应变作用下CrX单层的力学和电子性质。我们计算了两个不同应变方向（锯齿形和扶手椅形）下应变相关的能量、应力-应变关系、电子定位函数和电子态密度。我们的结果表明，在锯齿形和扶手椅形方向的宽应变范围内，铁磁相仍然是磁基态。这两个方向之间的力学响应表现出明显的各向异性，这在应力-应变关系的最大值中得到体现。随着卤原子X变重，锯齿形（扶手椅形）方向的最大应力从6.04（6.40）GPa降至3.20（3.33）GPa。通过分析电子定位函数，我们展示了应变引起的键合特性变化及其对材料机械强度的影响。我们还观察到电子态密度中Cr-d和X-p轨道的应变诱导能隙分裂，以及电子能带结构中的应变诱导带隙跃迁（从间接带隙到直接带隙），导致电子带隙减小，且对施加应变具有方向依赖性。我们的结果为单轴应变对CrX单层力学和电子性质的影响提供了基本见解，这与其在应变工程电子学和自旋电子学中的潜在应用相关。
