학술논문

Search for ferromagnetism in Mn-doped lead halide perovskites.
Document Type
Article
Source
Communications Physics. 4/21/2023, p1-8. 8p.
Subject
*LEAD halides
*FERROMAGNETISM
*MAGNETIC circular dichroism
*PEROVSKITE
*REMANENCE
*QUANTUM interference devices
*SOFT X rays
*MAGNETIC entropy
Language
ISSN
2399-3650
Abstract
Lead halide perovskites are new key materials in various application areas such as high efficiency photovoltaics, lighting, and photodetectors. Doping with Mn, which is known to enhance the stability, has recently been reported to lead to ferromagnetism below 25 K in methylammonium lead iodide (MAPbI3) mediated by superexchange. Two most recent reports confirm ferromagnetism up to room temperature but mediated by double exchange between Mn2+ and Mn3+ ions. Here we investigate a wide concentration range of MAMnxPb1−xI3 and Mn-doped triple-cation thin films by soft X-ray absorption, X-ray magnetic circular dichroism, and quantum interference device magnetometry. The X-ray absorption lineshape shows clearly an almost pure Mn2+ configuration, confirmed by a sum-rule analysis of the dichroism spectra. A remanent magnetization is not observed down to 2 K. Curie-Weiss fits to the magnetization yield negative Curie temperatures. All data show consistently that significant double exchange and ferromagnetism do not occur. Our results show that Mn is not suitable for creating ferromagnetism in lead halide perovskites. There have been recent studies reporting that Mn-doped MAPBI3 houses a ferromagnetic phase mediated by a double exchange mechanism. Here, however, using X-ray magnetic circular dichroism and magnetic susceptibility measurements, the authors uncover contradicting experimental evidence to indicate an absence of magnetic ordering in this material, suggesting that our understanding of Mn-doped lead halide perovskites may need reassessing. [ABSTRACT FROM AUTHOR]