NMR study of defect-induced magnetism in methylammonium lead iodide perovskite
Abstract
In organic-inorganic perovskite semiconductor methylammonium lead iodide the occurrence of magnetism has been confirmed from magnetization and 1H nuclear magnetic resonance (NMR) measurements. From room temperature down to 4 K, the magnetization is a combination of weak ferromagnetism and paramagnetism. 1H NMR spectra at low temperatures also reveal two components, one with a small chemical shift characteristic of 1H resonance in nonmetals, and the other with a much larger shift of ∼-100 ppm that is ascribed to the ferromagnetism of the material. The analysis of NMR spectra as well as that of 1H spin-lattice relaxation rate (1 /T1 ) indicates that disorder produces an inhomogeneous distribution of magnetic moments that order ferromagnetically where they are dense enough and otherwise behave as random paramagnetic impurities. It is shown that magnetism arises from iodine and lead vacancies present in the orthorhombic and cubic crystal phases of the material.
- Publication:
-
Physical Review B
- Pub Date:
- March 2020
- DOI:
- 10.1103/PhysRevB.101.094417
- Bibcode:
- 2020PhRvB.101i4417B