A first-principles DFT+ GW study of spin-filter and spin-gapless semiconducting Heusler compounds

Abstract

Among Heusler compounds, the ones being magnetic semiconductors (also known as spin-filter materials) are widely studied as they offer novel functionalities in spintronic and magnetoelectronic devices. The spin-gapless semiconductors are a special case. They possess a zero or almost-zero energy gap in one of the two spin channels. We employ the GW approximation to simulate the electronic band structure of these materials. Our results suggest that in most cases the use of GW self energy instead of the usual density functionals is important to accurately determine the electronic properties of magnetic semiconductors.

Simulation study of ballistic spin-MOSFET devices with ferromagnetic channels based on some Heusler and oxide compounds

“…However, the effective masses, band degeneracies, and band splittings for each compound we consider are extracted from DFT data that are presented in various references in existing literature and summarized in Table 1. 14,[17][18][19] We consider only the bands around the Fermi level, which are more involved in transport (lower CBs and higher VBs), in the directions X for Mn2CoAl and CoVZrAl and K for CrVZrAl. In the case of the oxide NiFe2O4, we adopt an average conductivity effective mass…”

“…Mn2CoAl (see also Table 1). 14,17,18 Figure 1c summarizes the SP dependence of the materials with different bandstructure parameters. Starting from the bandstructure we show in Fig.…”

“…Ferromagnetic semiconducting Heuslers, also named 'spin filters', have been studied only recently. 14,18 There is a large number of unexplored Heusler compounds, which means that the search for ferromagnetic Heusler semiconductors with larger EG ↑ and possibly lower masses (≤ 0.1m0) is required and timely.…”

“…The effective masses and band offsets are as explained extracted from bulk DFT data as shown in Table 1. 14,[17][18][19]…”

“…Table 1contains the bandstructure effective mass and band splitting data, extracted from DFT calculations in literature, used here for the real material simulations, Mn2CoAl (10 bands),17 CrVZrAl (12 bands),18 CoVZrAl (10 bands),14 and Ni2FeO4 (16 bands) 19. The lattice parameters are 0.5798 nm, 0.641 nm, 0.626 nm and 0.833 nm for Mn2CoAl, CrVZrAl, CoVZrAl and NiFe2O4, respectively.…”