Abstract
We demonstrate an alternative scheme for realizing spin polarizations in semiconductor nanostructures by an all-electric way. The electronic and magnetic properties of the model system, zigzag pristine boron nitride nanotubes (BNNTs), are investigated under a transverse electric field (E) through spin-polarized density functional theory calculations. As E increases, the band gap of BNNTs is reduced due to charge redistribution induced by the asymmetry of electrostatic potential energy, and BNNTs experience rich phase transitions, such as semiconductor-metal transition and nonmagnetic (NM) metal-ferromagnetic (FM) metal transitions. Electric-field-induced magnetization occurs when a sufficiently high density of states at the Fermi level in the vicinity of metal-insulator transition is reached due to the redistribution of electronic bands and charge transferring across the BNNTs. Further analysis show that the spontaneous magnetization is derived from the localized nature of the 2p states of B and N, and the ferromagnetic coupling is stabilized by Zener’s double-exchange mechanism. Our results may provide a viable way to realize spintronic devices for applications.
Highlights
Since the spin field-effect transistor (SpinFET) was first proposed by Datta and Das in 19901, many efforts have been put into the search for reliable mechanisms for manipulations of spin polarizations, including spin injection, spin transport and spin detection, in semiconductors
Without those structural engineering, we will demonstrate that applying a transverse electric field E can induce spontaneous magnetization in pristine boron nitride nanotubes (BNNTs), which may be desirable for the applications of spintronic devices
The present calculations are performed using Vienna ab initio simulation package (VASP)[21] which is based on density functional theory (DFT) with generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE)[22] for the exchange correlation potential, as it is proved that local density approximation (LDA) is always poor for BN or GaN semiconductors[23,24,25]
Summary
Since the spin field-effect transistor (SpinFET) was first proposed by Datta and Das in 19901, many efforts have been put into the search for reliable mechanisms for manipulations of spin polarizations, including spin injection, spin transport and spin detection, in semiconductors. Pristine BNNTs are NM materials, while the magnetic properties can be modified by structural modifications of BNNTs. Recent theoretical advances demonstrate that magnetization of BNNTs can be tuned by doping various atoms (O, C, Ge, Be, Cr, Mn, et al.15–17), carrier injection[18], and adsorption of H atoms[19] and F atoms[20]. Recent theoretical advances demonstrate that magnetization of BNNTs can be tuned by doping various atoms (O, C, Ge, Be, Cr, Mn, et al.15–17), carrier injection[18], and adsorption of H atoms[19] and F atoms[20] Without those structural engineering, we will demonstrate that applying a transverse electric field E can induce spontaneous magnetization in pristine BNNTs, which may be desirable for the applications of spintronic devices. The rich phase transitions that the pristine BNNTs experiences, for instance, semiconductor-metal transitions and NM metal-FM metal transitions, will be explored and discussed
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
