Magnetic properties of defect-free and oxygen-deficient cubicSrCoO3−δ

Abstract

We investigated theoretically electronic and magnetic properties of the perovskite material SrCoO 3−δ with δ ≤ 0.15 using a projector-augmented plane-wave method and a Green's function method. This material is known from various experiments to be ferromagnetic with a Curie temperature of 260 K to 305 K and a magnetic moment of 1.5 µB to 3.0 µB. Applying the magnetic force theorem as it is formulated within the Green's function method, we calculated for SrCoO 3−δ the magnetic exchange interactions and estimated the Curie temperature. Including correlation effects by an effective U parameter within the GGA+U approach and verifying this by hybrid functional calculations, we obtained the Curie temperatures in dependence of the oxygen-deficiency close to the experimental values.

Contribution of on-site Coulomb repulsion energy to structural, electronic and magnetic properties of SrCoO3 for different space groups: first-principles study

“…On the other hand, for U 9 eV, smeared Co 3d-e g and spin-up Co 3d-t 2g states are below E F due to the hybridization with O 2p states. These results are similar to those of previous results [13,15] but are different from the picture of IS-state t 2g [49]. However, the configuration of t 4 2g e 1 g in IS-state is reproduced by our calculations.…”

“…As also seen for Pm3m space group, the spin-down Co 3d-t 2g states overlap the spin-down Co 3d-e g states above E F . These results are also similar to the previously reported [13,15] but are different from the picture of IS-state Co 3d-t 2g [49]. Interestingly, t 4 2g e 1 g configuration is also reproduced with P4/mbm space group.…”

“…The ferromagnetic behavior is reflected by PDOS for all U values and it is mainly contributed by Co 3d states hybridized with O 2p states. We also suggest that the SrCoO 3 has metallic character, as reported in the previous reports [9,15], which is summarized in Table 2 and Table 3. We thus propose that the values of U = 8 eV and J = 0.75 eV are the best values for SrCoO 3 with Pm3m space group.…”

Formation and Migration of Oxygen Vacancies in SrCoO3 and Their Effect on Oxygen Evolution Reactions

“…19 The formal oxidation state of the B sites in an ABO 3 compound is generally determined by the oxidation state of the A site, which in this case leaves Co with a 4+ charge, which allows for the possibility of several spin states due to the presence of unpaired electrons. 20 Magnetic moments ranging from 1.5 ߤ to 3.0 ߤ have been predicted. 20 In our model the calculated magnetic moment was found to be 1.8 μ .…”

“…20 Magnetic moments ranging from 1.5 ߤ to 3.0 ߤ have been predicted. 20 In our model the calculated magnetic moment was found to be 1.8 μ . This low magnetic moment qualitatively agrees with the intermediate 20 In this work we will employ the PBEsol functional to study the oxygen vacancies and their diffusion.…”