Bipolar magnetic semiconductors: a new class of spintronics materials

Abstract

Electrical control of spin polarization is very desirable in spintronics, since electric fields can be easily applied locally, in contrast to magnetic fields. Here, we propose a new concept of bipolar magnetic semiconductors (BMS) in which completely spin-polarized currents with reversible spin polarization can be created and controlled simply by applying a gate voltage. This is a result of the unique electronic structure of BMS, where the valence and conduction bands possess opposite spin polarization when approaching the Fermi level. BMS is thus expected to have potential for various applications. Our band structure and spin-polarized electronic transport calculations on semi-hydrogenated single-walled carbon nanotubes confirm the existence of BMS materials and demonstrate the electrical control of spin-polarization in them.

Understanding the structural, electrical, and optical properties of monolayer h-phase RuO2 nanosheets: a combined experimental and computational study

“…Notably, the origin of magnetism in distorted h-RuO 2 NSs should be different from that of similar low-dimensional materials, such as graphene nanoribbons or hydrogenated SiC, in which the magnetism originates from chemical doping 28 . In distorted h-RuO 2 NSs, direct Ru-Ru metal-metal bonding can induce the stable FM state 29 , and we plan to investigate this in our future work.…”

Electrical control of carriers' spin orientation in the FeVTiSi Heusler alloy

“…Δ1 represents the spin-flip gap between VB and CB edges from different spin channels. Δ1+Δ2 and Δ1+Δ3 reflect the spin-conserved gaps for two spin channels, respectively [13]. For FeVTiSi alloy, we predict Δ1= 1.26 eV, Δ2= 0.36 eV and Δ3= 0.27 eV.…”

“…The magneto-electric effect in multiferroic systems also provides a feasible route to control of magnetism by electric field [12]. Theoretically, a new class of spintronic materials, bipolar magnetic semiconductors (BMS), were also proposed for this purpose [13,14]. In BMS, the valence bands (VB) and conduction bands (CB) are fully spin-polarized in the opposite spin directions, i.e.…”

“…Moreover, the control of spin in BMS does not rely on any varying g-tensor, spin-orbital coupling or magneto-electric effect, and is more convenient to implement. Though some BMS materials have been found [13][14][15][16][17][18][19][20][21][22][23][24][25], their applications are hindered either by the difficulty in experimental preparation or the low Curie temperature. It is still a big challenge to find BMS materials available at room temperature.…”

Edge hydrogenation-induced spin-filtering and negative differential resistance effects in zigzag silicene nanoribbons with line defects

“…In addition, the whole bottom conduction and top valence bands in M5 belong to different spin channels completely, that reveals a typical bipolar character for spintronic applications. 39 From the band structures of 57-defect ZSiNRs as displayed in M8-M10, it can be viewed that the energy bands of spin-up and spin-down in M8-M10 split obviously. It suggests the intense spin polarization occurs when 57-defect ZSiNRs are hydrogenated by two H atoms.…”