Half metallicity and magnetic properties of CrO2 doped with Ti, Sn or Ru

• First principle study of Ti, Sn or Ru doped CrO2 found that the half metallic nature of CrO2 will keep intact when doped with Ti or Sn, while it may be destroyed when doped with Ru.
• The half metallicity of Ru-doped CrO2 depends on Ru concentration as well as the relative positions of Ru ions.
• The magentic properties of doped CrO2 show dependence on both dopant concentration and dopant type.
• Large magnetocrystalline anisotropy may be induced in Ru-doped CrO2.

It is possible to stabilize CrO2 internally by doping with element such as Ti, Sn or Ru which has stable rutile structured oxide. However, the half metallicity and magnetic properties of CrO2 may also change when doped with different elements. In this study, by using first principle method, the electronic structure and magnetic properties of CrO2 doped with different amounts and different types (Ti, Sn or Ru) of dopants were studied. It was found that when doped with Ti or Sn, the half metallicity of CrO2 will keep intact even at very high dopant concentration, while for Ru-doped CrO2, the half metallicity will only be maintained at low Ru concentration. Besides, the half metallicity of Ru-doped CrO2 also depends on the relative positions of Ru atoms – the half metallicity may be destroyed even at low Ru concentration if two Ru ions are very close to each other. The magnetic properties of doped CrO2 also show dependence on dopant concentration and dopant type. The magnetocrystalline anisotropy (MAC) of Ru-doped is found to be very sensitive to both Ru concentration and relative positions of Ru atoms. Large MAC may be induced by Ru doping.