Magnetism in solids generally originates from the localized d or f orbitals that are hosted by heavy transition-metal elements. Here, we demonstrate a mechanism for designing a half-metallic f-orbital Dirac fermion from superlight sp elements. Combining first-principles and model calculations, we show that bare and flat-band-sandwiched (FBS) Dirac bands can be created when C20 molecules are deposited into a two-dimensional hexagonal lattice, which are composed of f-molecular orbitals (MOs) derived from sp-atomic orbitals (AOs). Furthermore, charge doping of the FBS Dirac bands induces spontaneous spin polarization, converting the system into a half-metallic Dirac state. Based on this discovery, a model of a spin field effect transistor is proposed to generate and transport 100% spin-polarized carriers. Our finding illustrates a concept to realize exotic quantum states by manipulating MOs, instead of AOs, in orbital-designed molecular crystal lattices.
|Original language||English (US)|
|Journal||Physical Review B|
|State||Published - Aug 23 2017|
Bibliographical noteFunding Information:
B.C. acknowledges the support from NSFC (Grant No. 11404188) and China Scholarship Council (Grant No. 201406225022). B.H., K.-H.J., W.J., and F.L. acknowledge the support from the U.S. DOE-BES (Grant No. DE-FG02-04ER46148). B.H. also acknowledges the support from NSFC (Grant No. 11574024) and NSAF (Grant No. U1530401). We thank the CHPC at the University of Utah for providing the computing resources.
© 2017 American Physical Society.