Doping-Induced Half-Metallic Ferromagnetism in Vanadium and Chromium-Doped Alkali Oxides K2O and Rb2O: Ab Initio Method

• Published in: Journal of superconductivity and novel magnetism 2017-08, Vol.30 (8), p.2197-2210
• Main Authors: Amine Monir, Mohammed El, Baltach, H., Abdiche, A., Al-Douri, Y., Khenata, R., Omran, S. Bin, Wang, X., Rai, D. P., Bouhemadou, A., Ahmed, W. K., Voon, C. H.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Strongly Correlated Systems; Superconductivity
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-017-4021-9

The electronic structures and magnetic properties of K 2 O and Rb 2 O alloys doped simultaneously with Cr and V transition elements were investigated using the full-potential linearized augmented plane wave plus local orbital (FP-LAPW + lo) method within the spin-polarized density functional theory (Spin-DFT) and implemented in the WIEN2k package, where the exchange-correlation potential in this approach is described by the generalized gradient approximation with Coulomb repulsion (GGA + U). The substitution of transition metals at 25 % ratio yields the magnetic characteristic of half-metallic ferromagnetism for K 2 O and Rb 2 O alloys. The structural properties were estimated in both magnetic and non-magnetic phases, demonstrating the stable ferromagnetic ground phase. The analysis of the electronic structure reveals the excellent half-metallic ferromagnetic nature, with a clear half-metallic gap ( E HM ) of 0.20 eV for K 1.75 Cr 0.25 O alloy. The exploitation of the electronic structure mainly served to determine the spin-polarized exchange-splitting energies Δ x ( d ) and Δ x ( pd ) generated by 3d -TM states, shows that the effective potential of the minority spin is more attractive than that of the majority spin. Moreover, the s − d exchange constant N 0 α (conduction band) and p − d exchange constant N 0 β (valence band) describe their contributions during the exchange splitting process. The magnetic properties have indicated that these alloys acquire a magnetic moment when the non-magnetic system is doped with a transition metal (TM). The obtained results from the important magnetic moments of these alloys indicate the potential for their use in spintronic devices.