Half-metallicity feature within Ag-doped zincblende WGe alloys: DFT plus U insights

By employing the full-potential linearized augmented plane wave (FP-L/APW+lo) technique based on density functional theory (DFT), the structural, electronic and magnetic properties of zincblende W(1-x)AgxGe alloys (x=0 and 0.25) are scrutinized thoroughly. Based on the generalized gradient approximation (GGA), the exchange-correlation energy functional is included in the current simulation. For computing the structural features, the GGA approximation is applied, whereas GGA, GGA+U and the modified Burke-Johnson of GGA+U (TB-mBJ-GGA+U) approximations are incorporated to perform the calculations of electronic and magnetic behaviors of these alloys. The structural analysis of the alloys indicated that the total energy of the W0.75Ag0.25Ge alloy was favorable in the ferromagnetic ground state. The spin-polarized electronic structure shows the half-metallic behavior of the W0.75Ag0.25Ge alloy, while the WGe compound is identified as a metal. The magnetic results obtained from the half-metallic W0.75Ag0.25Ge alloy increasingly support the full half-metallicity of this compound because an integer value is acquired for the total magnetic moment. The strong hybridization between 4p-Ge and 3d-W states brings forth weak local magnetic moments at the nonmagnetic Ge atomic sites and reduces the local magnetic moment of the W atomic sites from its free space charge.