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

Abstract

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 (∼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.

Understanding enormous redshifts in highly concentrated Mn2+ phosphors

“…This is not observed. In other reports where strongly redshifted emission in concentrated Mn 2+ phosphors is reported 26–35 also no corresponding significant change in the excitation or absorption spectra is observed while it would be expected for such strong exchange coupling. Only for γ-MnS an additional 606 nm excitation band appeared in the excitation spectrum of the NIR but this can be due to direct excitation of the NIR emitting centers.…”

“…19–25 In the past decade a new emission was reported for Mn 2+ : NIR emission from exchange coupled Mn 2+ -pairs. 25–34 This broad band NIR emission was observed in a variety highly doped Mn 2+ phosphors and deemed promising for applications in both lighting and sensing.…”

Mn2+‐Based Luminescent Metal Halides: Syntheses, Properties, and Applications

“…[3,4,10,11] To address these issues, the equivalent and heterovalent substitution strategy has been proposed via replacing Pb with Sn(II), [12,13] Sn(IV), [14][15][16][17] Bi(III), [18][19][20][21] Sb(III), [22][23][24][25][26] Cu(I), [6][7][8]27] In(III), [28][29][30][31][32][33] or Mn (II). [34][35][36][37][38][39][40][41][42] In particular, Mn 2+ -based metal halides have drawn intensive attentions owing to their high emission quantum efficiency, long-lived phosphorescence emission, flexible design in molecular structure, ease of synthesis, rich physical properties (e.g., triboluminescence and stimuli-responsivity), low cost, and low toxicity. Mn 2+ -based metal halides can give out red and green emissions depending on the coordination environments of Mn 2+ ions.…”

Angular Jahn–Teller Effect and Photoluminescence of the Tetrahedral Coordinated Mn2+ Activators in Solids–A First-Principles Study

“…8 The effects of Mn−Mn magnetic coupling on the photoluminescence have been reported in CsMnF 3 . 9 Besides, with the near-spherical electronic distribution of the d 5 ground state, Mn 2+ activators have been extensively studied for the abundant site occupancy, 10,11 the Jahn−Teller effect in the excited states, 12−14 and for phosphor-converted white lightemitting diodes to compensate the broad orange-red and red components in emission spectra. 15−18 Mn 2+ -doped ZnS or ZnSe nanocrystals have been widely studied for decades for the Jahn−Teller effect in the excited states 12,13 and recently for the ferromagnetic excited states of Mn 2+ dimers.…”

“…For instance, the multiferroic fluoroperovskite NaMnF 3 has been extensively studied for information storage and spintronics. − MnBi 2 Te 4 materials have been studied as antiferromagnetic topological insulators, Mn-doped II–VI compounds have been studied for dilute magnetic semiconductors, and MnV 2 O 4 materials have been studied for the spin–orbital-lattice coupling . The effects of Mn–Mn magnetic coupling on the photoluminescence have been reported in CsMnF 3 …”