2017/09/30 by Taekoo Oh, Hiroaki Ishizuka, Bohm‐Jung Yang +1
Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Band gap #Condensed matter physics #Electronic band structure #Magnetic field #Magnetic moment #Multiferroics and related materials #Paramagnetism #Physics #Pyrochlore #Quantum Hall effect #Quantum anomalous Hall effect #Quantum mechanics #Semimetal #Topological Materials and Phenomena #Topology (electrical circuits) #Zeeman effect #Zeeman energy #cond-mat.mes-hall #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.98.144409
published as Phys. Rev. B 98, 144409 (2018) · 22 pages, 18 figures
arxiv created 2018/09/21 · openalex created_date 2018/09/27 · openalex publication_date 2018/10/08 · arxiv updated 2018/10/10 · openalex updated_date 2026/08/06
Motivated by the recent experimental observation of anomalous magnetotransport properties near the Mott quantum critical point (QCP) of pyrochlore iridates, we study the generic topological band structure near QCP in the presence of magnetic field. We have found that the competition between different energy scales can generate various topological semimetal phases near QCP. Here the central role is played by the presence of a quadratic band crossing (QBC) with fourfold degeneracy in the paramagnetic band structure. Due to the large band degeneracy and strong spin-orbit coupling, the degenerate states at QBC can show an anisotropic Zeeman effect as well as the conventional isotropic Zeeman effect. Through the competition between three different magnetic energy scales including the exchange energy between Ir electrons and two Zeeman energies, various topological semimetals can be generated near QCP. Moreover, we have shown that these three magnetic energy scales can be controlled by modulating the magnetic multipole moment (MMM) of the cluster of spins in a unit cell, which can couple to the intrinsic MMM of the degenerate states at QBC. We propose the general topological band structure under magnetic field achievable near QCP, which would facilitate the experimental discovery of novel topological semimetal states in pyrochlore iridates.