Vacancy-induced insulator – direct spin gapless semiconductor – half-metal transition in double perovskite La2CrFeO6: A first-principles study

• La vacancy is introduced in La2CrFeO6.
• La1.75CrFeO6 shows the direct spin gapless semiconductor.
• La1.5CrFeO6 behaves as half-metal with the half-metallic gap of 0.42 eV.

Double perovskite oxide La2CrFeO6 with the characteristic of ferrimagnetic insulator has been reported by Chakraverty and Lee et al. Engineering the physical properties of materials, including obtaining unusual properties, can be achieved by some measures, and defect-tuning has been one of the most efficient measures. Here, by using density-functional calculations, La vacancy is introduced in La2CrFeO6 and special properties are obtained successfully. The results show that the magnetic phase of La2CrFeO6 would transfer from ferrimagnetic to ferromagnetic ordering as long as La vacancy is introduced. Furthermore, La1.75CrFeO6 shows direct spin gapless semiconductor, and La1.5CrFeO6 behaves as half-metal with the half-metallic gap of 0.42 eV. In the whole range of La vacancy, the electronic configurations of both Cr and Fe ions exhibit high-spin states, the magnetic moment of Fe remains 4.20 μB, while that of Cr ions decreases from 2.66 to 1.97 μB with increasing the amount of La vacancy. This work opens an alternative way to design spintronic materials, especially for direct spin gapless semiconductors which have never been reported in perovskite oxides.