MnPO₄: A Novel Candidate for Spintronics and Topological Applications

Quantum materials, which host multiple quantum phenomena, attract the scientific world due to the fundamental and application point of view. We present a novel candidate MnPO₄, recipient of requisite bulk and surface electronic structure properties for hosting two distinct quantum phenomena such as the non-trivial topological magnetic Weyl fermionic state  and spin-gapeless semiconducting (SGS) nature, and hence MnPO₄ turns to be a Composite quantum compound(CQC), which is very rare in condensed matter systems. A detailed investigation based on first principles density functional theory (DFT) reveals the SGS behaviour, where one spin channel shows the semiconducting nature and the other spin channel shows the zero band gap nature. Further, a drumhead like surface state originated from a nodal loop around Y high symmetry point in the Brillouin zone is identified. We have also traced the surface states emerged from the distinct Weyl nodes appeared in the presence of spin-orbit coupling. A large value of AHC of 1265 Ω^-1 cm^-1 is observed in our proposed compound at around -1.37 eV below the Fermi level.