Electronic properties of magnetic semiconductor CuMnO_2 : a first principles study

Geometrically frustrated magnetic semiconductor CuMnO_2 has potential applications as photo-catalyst, in photochemical cells and multi-ferroic devices. Electronic band structure in the antiferromagnetic and ferromagnetic phases of CuMnO_2 were calculated using first principle density functional theory (DFT) as implemented in VASP. Electronic band structure in the antiferromagnetic state shows indirect band gap (∼ 0.53 eV) where as in the ferromagnetic state it shows half-metallic state with 100% spin polarization. The half-metallic state arises due to double exchange mechanism. In the half-metallic state the density of states for the up spin channel shows asymmetric power law behaviour near the Fermi level while the down spin channel shows fully gapped behaviour. The calculated magnetic moment of Mn atom in the ferromagnetic (3.70 μ_B) and antiferromagnetic (3.57 μ_B) states are consistent with experimental values. Our calculation predicts potential application of CuMnO_2 in spintronic devices especially in the ferromagnetic state, as a spin injector for spin valves in spintronic devices.