Lattice-Distortion-Induced Change in the Magnetic Properties in Br-Defect Host CsPbBr3Perovskite Quantum Dots

Herein, we report temperature- and field-induced magnetic states in CsPbBr₃ perovskite quantum dots (PQDs) attributed to Br defects. We find that temperature-dependent structural distortion is the main source of various temperature-induced magnetic states in Br-defect host CsPbBr₃ PQDs. Comprehensively examined magnetization data through Arrott plots, Langevin and Brillouin function fitting, and structural analysis reveal the presence of various oxidation states (i.e., Pb⁰, Pb⁺, Pb²⁺, and Pb³⁺) yielding different magnetic states, such as diamagnetic states above 90 K, paramagnetic states below ≈90 K, and perhaps locally ordered states between 58 and 90 K. It is realized from theoretical fits that paramagnetic ions exist (i.e., superparamagnetic behavior) due to Br defects causing Pb⁺ (and/or Pb³⁺ ions) in the diamagnetic region. We anticipate that our findings will spur future research of the development of spin-optoelectronics, such as spin light-emitting diodes, and spintronics devices based on CsPbBr₃ PQDs.