论文标题
Janus Monolayer YBRI中的压电铁磁性：第一原则预测
Piezoelectric ferromagnetism in Janus monolayer YBrI: a first-principle prediction
论文作者
论文摘要
固有的铁磁和压电性的共存，即压电铁磁性（PFM），对于推进多功能自旋技术技术至关重要。在这项工作中，我们证明了Janus Monolayer YBRI是PFM，它在机械上是机械，机械和热稳定的。通过使用通用梯度近似以及$ u $（GGA+$ u $）方法研究了对YBRI物理特性的电子相关效应。对于平面外磁各向异性，YBRI是Ferrovalley（FV）材料，山谷分裂大于所考虑的$ U $范围的82 MeV。可以在平面内电场下实现异常的山谷大厅效应（AVHE）。但是，对于平面磁各向异性，YBRI是一种常见的铁磁（FM）半导体。在考虑固有的磁各向异性时，YBRI的易于轴始终是磁各向异性能量（MAE）从0.309 MeV到0.237 MeV（$ u $ = 0.0 ev至3.0 eV）。但是，可以通过外部磁场从面内到平面方向调节磁化强度，然后导致山谷极化的发生。此外，在YBRI单层中，缺失的中心对称性以及镜子对称性破坏导致平面内和平面外的压电。在典型的$ u $ = 2.0 eV处，$ d_ {11} $预计为-5.61 pm/v，它高于或与其他二维（2D）已知材料的$或比较。 YBRI的电子和压电性能可以通过施加双轴菌株有效调节。例如，拉伸应变可以增强山谷分裂和$ d_ {11} $（绝对值）。 YBRI的预测居里温度高于实验合成的2D铁磁材料$ \ MATHRM {CRI_3} $和$ \ MATHRM {CR_2GE_2TE_6} $。
Coexistence of intrinsic ferromagnetism and piezoelectricity, namely piezoelectric ferromagnetism (PFM), is crucial to advance multifunctional spintronic technologies. In this work, we demonstrate that Janus monolayer YBrI is a PFM, which is dynamically, mechanically and thermally stable. Electronic correlation effects on physical properties of YBrI are investigated by using generalized gradient approximation plus $U$ (GGA+$U$) approach. For out-of-plane magnetic anisotropy, YBrI is a ferrovalley (FV) material, and the valley splitting is larger than 82 meV in considered $U$ range. The anomalous valley Hall effect (AVHE) can be achieved under an in-plane electric field. However, for in-plane magnetic anisotropy, YBrI is a common ferromagnetic (FM) semiconductor. When considering intrinsic magnetic anisotropy, the easy axis of YBrI is always in-plane with magnetic anisotropy energy (MAE) from 0.309 meV to 0.237 meV ($U$=0.0 eV to 3.0 eV). However, the magnetization can be adjusted from the in-plane to off-plane direction by external magnetic field, and then lead to the occurrence of valley polarization. Moreover, missing centrosymmetry along with mirror symmetry breaking results in both in-plane and out-of-plane piezoelectricity in YBrI monolayer. At a typical $U$=2.0 eV, the $d_{11}$ is predicted to be -5.61 pm/V, which is higher than or compared with ones of other two-dimensional (2D) known materials. The electronic and piezoelectric properties of YBrI can be effectively tuned by applying a biaxial strain. For example, tensile strain can enhance valley splitting and $d_{11}$ (absolute value). The predicted Curie temperature of YBrI is higher than those of experimentally synthesized 2D ferromagnetic materials $\mathrm{CrI_3}$ and $\mathrm{Cr_2Ge_2Te_6}$.
