磁性体におけるモノポール結晶の理論的研究

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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.