Palladium (III) Fluoride Bulk and PdF3/Ga2O3/PdF3 Magnetic Tunnel Junction: Multiple Spin-Gapless Semiconducting, Perfect Spin Filtering, and High Tunnel Magnetoresistance.

Zongbin Chen,Heju Xu,Yongchun Gao,Xiaotian Wang,Tie Yang,Tingzhou Li,Rabah Khenata

doi:10.3390/nano9091342

Abstract

Spin-gapless semiconductors (SGSs) with Dirac-like band crossings may exhibit massless fermions and dissipationless transport properties. In this study, by applying the density functional theory, novel multiple linear-type spin-gapless semiconducting band structures were found in a synthesized -type bulk PdF3 compound, which has potential applications in ultra-fast and ultra-low power spintronic devices. The effects of spin-orbit coupling and on-site Coulomb interaction were determined for the bulk material in this study. To explore the potential applications in spintronic devices, we also performed first-principles combined with the non-equilibrium Green’s function for the PdF3/Ga2O3/PdF3 magnetic tunnel junction (MTJ). The results suggested that this MTJ exhibits perfect spin filtering and high tunnel magnetoresistance (~5.04 × 107).

Highlights

SGSs possess a gapless feature in one spin channel and a semiconducting gap in the other spin channel
Parabolic SGSs show a quadratic band dispersion for gapless bands, while Dirac-like crossing SGSs (DSGSs) exhibit a linear band dispersion at the Fermi level in one spin channel. Due to this unique dispersion, the effective electron quantity can be eliminated in DSGSs
In PC, results reveal that the transmission coefficient of spin-up electrons at the Fermi level is much higher than that of spin-down electrons, showing that the major contribution of current comes from the spin-up electrons

Summary

Introduction

SGSs possess a gapless feature in one spin channel and a semiconducting gap in the other spin channel. In terms of differences in the dispersion of its band structures near the Fermi level, SGSs can be divided further into parabolic or Dirac-like crossing types. Parabolic SGSs show a quadratic band dispersion for gapless bands, while Dirac-like crossing SGSs (DSGSs) exhibit a linear band dispersion at the Fermi level in one spin channel.

Results

Conclusion