High-pressure synthesis of A-site ordered perovskite PbMn 3 (CrMn 3 )O 12 with long-range antiferromagnetic ordering and a spin glass transition.

An AA' 3 B 4 O 12 -type perovskite oxide PbMn 3 (CrMn 3 )O 12 was synthesized by high-pressure solid-state reactions at 8 GPa and 1373 K. Synchrotron X-ray diffraction shows a cubic crystal structure with the space group Im 3̄. The charge states are verified by X-ray photoelectron spectroscopy to be PbMn 3+ 3 (Cr 3+ Mn 3+ 2 Mn 4+ )O 12 , where the Pb 2+ and Mn 3+ are 1 : 3 ordered respectively at A and A' sites, while the Cr 3+ , Mn 3+ and Mn 4+ are disorderly distributed at the B site. PbMn 3 (CrMn 3 )O 12 features a long-range antiferromagnetic order of A'-site Mn 3+ spins at about 66 K and a subsequent spin glass transition around 36 K due to the randomly distributed Cr 3+ , Mn 3+ , and Mn 4+ cations at the B site. This unique stepwise order of A' and B-site spins indicates weak A'-B site spin interactions, which are dominated by the difference in the B-site Mn 3+ /Ni 2+ and Mn 4+ number in the quadruple perovskites AMn 3 B 4 O 12 .