Spin filtering with Mn-doped Ge-core/Si-shell nanowires

Abstract

Incorporating spin functionality into a semiconductor core–shell nanowire that offers immunity from the substrate effect is a highly desirable step for its application in next generation spintronics.

Cr-Doped Ge-Core/Si-Shell Nanowire: An Antiferromagnetic Semiconductor

“…It should be noted that in the case of Cr-doped GaN nanowire, FM ordering was reported to be the stable configuration arising from the double exchange interaction . In the case of the Mn-doped Ge-core/Si-shell nanowire, which is a half-metal, the FM spin ordering is found to be more favorable with an exchange energy of ∼90 meV, and a majority spin carriers exhibit a metallic behavior with a finite density of states at the Fermi energy . This suggests that the exchange interaction that stabilizes the FM ordering between Mn atoms in the Mn-doped nanowire is mediated by the itinerant electrons (majority spin carries in the metallic channel) at the Fermi energy.…”

“…46 In the case of the Mn-doped Ge-core/Si-shell nanowire, which is a half-metal, the FM spin ordering is found to be more favorable with an exchange energy of ∼90 meV, and a majority spin carriers exhibit a metallic behavior with a finite density of states at the Fermi energy. 33 This suggests that the exchange interaction that stabilizes the FM ordering between Mn atoms in the Mn-doped nanowire is mediated by the itinerant electrons (majority spin carries in the metallic channel) at the Fermi energy. However, in Cr-doped Ge-core/Si-shell nanowire, which is semiconducting (as discussed in the next paragraph), we find the AFM coupling between the localized d yz orbitals of the Cr atoms is found to be mediated by the p z orbitals of the bonded Ge atoms as shown in Figure 1d, suggesting that the superexchange mechanism is responsible for the stability of the AFM ordering.…”

“…Hence, the next question we need to answer: Is there any magnetic impurity that can transform this semiconductor nanowire to an AFM semiconductor? Because substitutional doping of Mn has been reported to transform this semiconducting material to a ferromagnetic half-metal, 33 the possibility of AFM semiconducting behavior with Cr-dopant is explored in this study.…”

PbTe(core)/PbS(shell) Nanowire: Electronic Structure, Thermodynamic Stability, and Mechanical and Optical Properties

“…Furthermore, the reported value of the ON state current in the core/shell semiconductor nanowire field effect transistors (FETs) is found to be 3–4 times higher compared to the state of the art metal oxide semiconductor field effect transistors (MOSFETs), indicating their superior performance; the core/shell semiconductor nanowire FETs also form essential components of the programmable logic circuits . In addition, the transition metal doped core/shell nanowires have been shown to act as an excellent spin filter and a high-performance switching device . Moreover, the core/shell nanostructures have been the subject of considerable interest for catalytic applications.…”