Emergent Relativistic Effects in Condensed Matter - From Fundamental Aspects to Electronic Functionality

Recently a great deal of attention has been focused on condensed matter systems which have zero-gap electronic structures analogous to the massless relativistic particles. The Weyl semimetal, which is recently discovered, has a peculiar band structure characterized by the nodal touching points (Weyl nodes) and the topological surface bands connecting the Weyl nodes. In this talk, I introduce our recent theoretical works to explore unconventional electronic properties of 3D nodal semimetals. First I present a systematic study of the magnetic susceptibility of the Weyl semimetals and line-node semimetals[1], where I show that the orbital diamagnetism always has a strong divergence right at the band touching energy, and also that the topological surface states contribute to unconventional susceptibility component which is referred to the spin-orbit cross term. In the latter half, I introduce the magnetopotical properties of so-called type-II Weyl semimetal, where the electron and hole pockets form a 8-shaped semiclassical orbit. I demonstrate the system exhibits a strong anisotropy in the cyclotron resonant frequencies, and it serves as a hallmark of 8shaped Fermi surface.[2] [1] M. Koshino and I. F. Hizbullah, Phys. Rev. B 93, 045201 (2016). [2] M. Koshino, Phys. Rev. B 94, 035202 (2016). Gastgeber: Prof. Dr. K. Richter