No abstract

The structural, electronic and magnetic properties of Cr, Mn, Fe, Co and Ni-doped bilayer WSe are predicted by using first principles calculations. The doped transition-metal (TM) atoms show a covalent-binding with the nearest Se atoms. The calculated electronic structures reveal that the TM Cr, Mn, Fe and Co-doped bilayer WSe exhibits a half-metallic character with a 100% spin polarization at the Fermi level, and the reason is ascribed to the strong hybridization peak between the transition metals and the parent W and Se atoms. The Ni-doped bilayer WSe is still a semiconductor with nonmagnetism. The Fe-doped system has a robust stability of half-metallicity because there are three connected states peak spanning the Fermi level. The doping of Cr, Mn, Fe and Co atoms leads to a prominent total magnetism (0.93-3.65 [Formula: see text] moment per unit cell), and an induced ∼0.3 [Formula: see text] moment in parent W atoms is found in addition to the main contribution of TM atomic magnetism (0.71-3.33 [Formula: see text] moment per atom). The predicted Cr, Mn, Fe and Co-doped bilayer WSe should be the candidate materials for spintronic devices due to their magnetic and half-metallic nature.

No abstract

The electronic structure, thermoelectric properties, and thermodynamic entropy of Ti2CrGe-doped Ti0.75HfMo0.25CrGe were investigated using first-principles calculations in combination with the semi-classical Boltzmann transport theory and a common thermodynamic formalism. The band structure was half-metallic with a narrow gap of 0.02 eV in the spin-down channel and metallic character in the spin-up channel. The calculated thermoelectric transport properties revealed that Ti0.75HfMo0.25CrGe exhibited a larger thermoelectric figure of merit ZT with a lower lattice thermal conductivity than its prototype alloy Ti2CrGe. In particular, the entropy of Ti0.75HfMo0.25CrGe was larger than that of Ti2CrGe in the temperature range of 0–1000 K. These results indicate that increasing the entropy is an effective approach for the design of high-performance thermoelectric materials and confirm the entropy “gene” in thermoelectric materials.

No abstract