We investigated the strain modulation of the magnetic states and interatomic exchange interactions in layered van der Waals magnet Fe₃GeTe₂ by detailed first-principles studies. The energy-minimum calculations demonstrate the ground state of bulk Fe₃GeTe₂ is weak antiferromagnetic coupling, in contrast to most precious reports, and it can be modulated to ferromagnetic coupling under small a-axis distortion (~2%). More importantly, we obtained the variation of exchange coupling parameters J_ij and Curie temperature T_C under both uniaxial and isotropic strain, and found the T_C can be enhanced to room temperature in the case of uniaxial lattice distortion, especially along the a-axis. Our work clarified the role of intra- and inter-layer magnetic coupling in tuning of the ground state magnetism that can be generally applied in two-dimensional layered materials and suggested a paradigm for tuning T_C with uniaxial strain in Fe₃GeTe₂.

我们通过详细的第一性原理研究了层状范德华磁体Fe ₃ GeTe ₂中的磁态应变调制和原子间交换相互作用。最少的能量计算表明，与大多数珍贵的报道相比，块状Fe ₃ GeTe ₂的基态是弱的反铁磁耦合，可以在较小的a轴畸变（〜2％）下将其调制为铁磁耦合。更重要的是，我们获得了在单轴和各向同性应变下交换耦合参数J _ij和居里温度T _C的变化，并得出了T _C在单轴晶格畸变的情况下，尤其是沿a轴，可将其提高至室温。我们的工作阐明了层内和层间磁耦合在基态磁性调谐中的作用，该状态通常可应用于二维层状材料，并提出了一种在Fe ₃ GeTe ₂中用单轴应变调谐T _C的范例。