Isolated-Mn2+-like Luminescent Behavior in CsMnF3 Caused by Competing Magnetic Interactions at Cryogenic Temperature

The effects of antiferromagnetic and ferromagnetic interactions between Mn2+ ions on its luminescence have been a profound but controversial topic in optoelectronic materials. This research uses the photomagnetism measurement and density functional theory calculation to reveal these effects in CsMnF3 with both of the aforementioned interactions and two distinguished emission peaks. It is found that the 600 and 795 nm emissions are raised from antiferromagnetic and ferromagnetic interactions, respectively. The photomagnetism data show larger or smaller magnetization for the photoexcited state compared to the unilluminated state when there is antiferromagnetic ordering or ferromagnetic ordering, respectively, which suggests the variation of spin states of coupled Mn2+ ions with the competitive magnetic interactions. It results in significantly long decay lifetimes (similar to ms) for both emissions at cryogenic temperature, which is like the behavior of isolated Mn2+ without magnetic interactions. The declining trends for their temperature-dependent decay lifetimes indicate their distinct origins, in which a stronger dependency for the 600 nm emission with antiferromagnetic coupling is observed. This research discloses magnetic interactions affecting Mn2+ luminescent properties, which will give some convincing perspectives to the debate on transition metal-doped optoelectronic materials and devices.