Ferromagnetic half-metallic characteristic and phase transition in rare-earth Yb doped SiC: A GGA+U study

The electronic, magnetic and structural properties of rare earth Yb doped on SiC are investigated theoretically based on the density functional theory (DFT). Both zincblende (ZB) and rocksalt (RS) structures of SiC have been calculated. We found that Si3YbC4 with ZB exhibits a complete half-metallic characteristic with a wide gap more than 1.8 eV using GGA and GGA+U methods. However, the half-metallicity is destroyed with RS. The sensitivity of magnetic moments of Si3YbC4 as a function of pressure is also discussed, there are two magnetic phase transition points with increased pressure. The exchange interaction between local Yb-4f electrons and conduction electrons plays an important role in their heavy fermion characters. The exchange splitting of the conduction band is confirmed to be much larger than that of the valence band in Si3YbC4, which makes the holes-mediated ferromagnetism in this material.