A computational material study of HoB6 and Co/MgO–HoB6: heavy rare-earth metal hexaborides

Abstract The superior physical and chemical properties of holmium hexaborides enable their use in high-tech industrial applications. It is vital to examine these structure types on the atomic scale to elucidate the details of their structure and improve their functional properties. For this reason, holmium hexaboride, cobalt–holmium hexaboride and magnesium oxide–holmium hexaboride crystal structures were investigated systematically employing ab initio material modeling, including the dispersion corrected density functional theory approach, using an interface to the PWscf code of Quantum Espresso and Vienna Ab initio Simulation Package software. The effects of cobalt (∼4 wt.%) and MgO (∼2.8 wt.%) doping on holmium hexaboride structures are discussed in terms of optical, magnetic, and electronic properties including the charge transform, scanning tunneling microscopy, density of states, and K-edge X-ray absorption spectra analyses. Scanning tunneling microscopy and K-edge X-ray absorption spectra analyses were conducted to enable correlation with future experiments. Results indicate that cobalt doping does not provide enough driving magnetic force to alter the magnetic properties of the HoB 6 . Furthermore, MgO addition leads to significant distortions in the structure of the HoB 6 . The properties of HoB 6 were affected adversely, especially due to the distorsion of the octahedral boron unit.