Design of half-metallic ferromagnetism in germanene/silicene hybrid sheet

•We perform first-principles calculation to study the two-dimensional germanene and silicene hybrid sheet (GeSiHS) saturated with brominate atoms (Br).•Half-brominated GeSiHS exhibits half-metallic character with 100% spin-polarized currents at the Fermi level.•The half-brominated GeSiHS consists of only sp elements.•The half-brominated GeSiHS is expected to be FM around room temperature with net magnetic moment 1.0 μB per unit cell.•The half-metallic character is expected to be robust because the partially filled bands result from a large number of holes.

In this theoretical work, we perform first-principles calculation to study the geometric, electronic, and magnetic properties of the two-dimensional germanene and silicene hybrid sheet (GeSiHS) saturated with brominate atoms (Br). Although the pristine GeSiHS is semi-metallic, half-saturation on only a single side of Si atoms with Br results in the localized and unpaired electrons in unsaturated Ge atoms, showing long-range ferromagnetic (FM) properties with a high Curie temperature. Interestingly, half-brominated GeSiHS exhibits half-metallic character with 100% spin-polarized currents at the Fermi level. These findings provide the possibility of GeSiHS as promising building blocks for spintronic devices.