Electronic and magnetic structure of cuprous oxide Cu2O doped with Mn, Fe, Co, and Ni: A density-functional theory study

We investigate the effect of transition metal (TM) substitution in cuprous oxide ${\mathrm{Cu}}_{2}\mathrm{O}$ on the basis of ab initio calculations employing density-functional theory $(\mathrm{GGA}+\mathrm{U})$. By using the supercell approach, we study the effect of substituting Cu by Mn, Fe, Co, and Ni, assuming both low TM concentrations (3.2%) in a cubic geometry and higher TM concentrations (9.1%) in a trigonal setup. For the elements Mn and Co, magnetic exchange constants up to the fifth nearest neighbor are calculated, assuming both cases, perfect $\mathrm{Mn}∕\mathrm{Co}:{\mathrm{Cu}}_{2}\mathrm{O}$ as well as defects in the host such as single copper and oxygen vacancies. Our results clearly show the importance of defects in these materials and thus offer an explanation for various, seemingly opposed, experimental results.