Ferromagnetism in alkali-metal-doped AlP: An ab initio study

• The magnetism induced by Li atom is negligible at 3.125% doping concentration.
• The magnetism tends to be FM state as the Li doping concentration decreases.
• Half-metallic characteristics were achieved in K-doped AlP with a HM gap.
• The ground state is AFM for the K-doped AlP, but PM for the Na-doped AlP.
• The magnetism derives from the p–p interaction mechanism.

By using first-principle calculations within the generalized gradient approximation, we investigated the magnetic and electronic properties of Group IA alkali-metal (Li, Na, K)-doped AlP. The main purpose of this study is to determine the effect that different types of alkali dopants have on the magnetic behavior of AlP. The magnetic moment induced by the Li dopant is negligible in (2 × 2 × 2) Li-doped AlP supercell. However, it is also found that the magnetism is affected by the Li doping concentration. The Na and K dopants in AlP induce a net magnetic moment of 2.0 μB. Half-metallic characteristics are achieved in K-doped AlP. The calculated density of states and the spin density distribution of Na- and K-doped AlPs show that the magnetism derives from the p–p interaction between the dopants and the neighboring anions. However, the spontaneous polarization cannot occur in Na-doped AlP. The K-doped AlP has the AFM ground state which is the unstable at room temperature. The results reveal that the Na- and K-doped AlPs are unlikely to be potential DMSs for the development of new spintronic devices.

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