磁性体におけるモノポール結晶の理論的研究

在过去的一个财政年度里，我们完成了两个研究课题，并且为了准备稿件，我们正在完成其他项目。继我们之前对光致Weyl半金属相和Weyl体系中的Tomonaga-Luttinger液体的研究之后，我们首先继续对Weyl半金属体系进行思考。我们解决了Weyl电子被球形阶跃势垒散射的问题。调整入射能量和势半径，可以同时进入准经典和量子状态。研究了与远场电流和积分截面相关的输运特征，揭示了优选的前向散射。研究结果将有助于运输研究和电子透镜在Weyl系统中的应用。我们还研究了在外加磁场作用下的纳米线Dirac/Weyl半金属。我们使用了几个连续体模型来考虑在晶格模型中难以处理的圆柱对称性。我们观察了纳米线拓扑半金属的各种效应。同时，在最新的手性晶格铁磁体Cu2OSeO3中声子的磁手性效应实验的激励下，我们正在尝试建立一个理论。高分辨率超声实验表明，声速在平行传播和反平行传播时相对于外部磁场是不同的。非互易的符号应取决于晶体的手性，并且信号应在磁有序温度以下和较高的超声频率下增强。

In the past fiscal year, we finished two research topics and are finalizing other projects for the sake of manuscript preparation. Following our previous works on photoinduced Weyl semimetal phases and Tomonaga-Luttinger liquid in Weyl systems, we first continue to think on Weyl semimetal systems.We solve the Weyl electron scattered by a spherical step potential barrier. Tuning the incident energy and the potential radius, one can enter both quasiclassical and quantum regimes. Transport features related to far-field currents and integrated cross sections are studied to reveal the preferred forward scattering. The findings will be useful in transport studies and electronic lens applications in Weyl systems.We also study the nanowire Dirac/Weyl semimetals under an external magnetic field. We use several continuum models to take account of the cylindrical symmetry that is formidable to deal with in lattice models. We observe various effects of the nanowire topological semimetal.Meanwhile, motivated by a latest experiment on the magnetochiral effect of phonon in a chiral-lattice ferrimagnet Cu2OSeO3, we are trying to make a theory. High-resolution ultrasound experiments reveal that the sound velocity differs for parallel and antiparallel propagation with respect to the external magnetic field. The sign of the nonreciprocity should depend on the chirality of the crystal and the signal should be enhanced below the magnetic ordering temperature and at higher ultrasound frequencies.