Coexistence of topological nontrivial and spin-gapless semiconducting behavior in MnPO4: A composite quantum compound
Chia-Hsiu Hsu1,4*, P. C. Sreeparvathy2, Chanchal K. Barman2, Feng-Chuan Chuang1,3,4, Aftab Alam2
1Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan
2Department of Physics, Indian Institute of Technology Bombay, Mumbai, India
3Department of Physics, National Tsing Hua University, Hsinchu, Taiwan
4Physics Division, National Center for Theoretical Sciences, Taipei, Taiwan
* Presenter:Chia-Hsiu Hsu,
Composite quantum compounds (CQC) are a classic example of quantum materials, which host more than one apparently distinct quantum phenomenon in physics. Magnetism, topological superconductivity, Rashba physics, etc. are a few such quantum phenomena, which are ubiquitously observed in several functional materials and can coexist in CQCs. In this paper, we use ab initio calculations to predict the coexistence of two incompatible phenomena, namely topologically nontrivial Weyl semimetal and spin-gapless semiconducting (SGS) behavior, in a single crystalline system. SGS belongs to a special class of spintronics material, which exhibits a unique band structure involving a semiconducting state for one spin channel and a gapless state for the other. We report such an SGS behavior in conjunction with the topologically nontrivial multi-Weyl fermions in MnPO4. Interestingly, these Weyl nodes are located very close to the Fermi level with the minimal trivial band density. A drumhead-like surface state originating from a nodal loop around the Y point in the Brillouin zone is observed. A large value of the simulated anomalous Hall conductivity (1265 Ω-1cm-1) indirectly reflects the topological nontrivial behavior of this compound. Such co-existent quantum phenomena are not common in condensed matter systems and hence it opens up a fertile ground to explore and achieve newer functional materials.

Keywords: composite quantum compounds, topological Weyl semimetal, spin-gapless semiconducting, density functional theory