Extrinsic room-temperature ferromagnetism in MoS2

• DOI: 10.1007/s10853-021-05916-z
• Publication Date: 2021-03-02T15:02:42Z
• Authors: Sabyasachi Saha; Manuel Bañobre-López; Oleksandr Bondarchuk; Joaquín Fernández...; Francis Leonard D...
• Keywords: Diamagnetism; Magnetism; Magnetic semiconductor

We report stable room-temperature ferromagnetism in commercially available MoS2 powder with a nominal purity greater than 98%. In order to assess the origin of the unexpected ferromagnetic signal, we carried out thorough characterization of the samples, by a combination of X-ray diffraction, Raman spectroscopy, electron microscopy, X-ray photoelectron spectroscopy and superconducting quantum interference device magnetometry. Using secondary ion mass spectrometry, we infer that up to 1.6% of a pool of different external dopants, including 0.8% of Fe and others, are present in the MoS2 samples. We find very low value of magnetic moment per unit formula that, together with the small density of magnetic dopants, and the room-temperature magnetic order, leads us to conclude that ferromagnetism is not hosted at the MoS2 crystal but can be ascribed to secondary phase of transition metal atoms’ clusters that aggregate. Our results stress the need of a careful characterization of transition metal dichalcogenides in the study of magnetism and spintronics involving either nominally pure MoS2 as a diamagnetic semiconductor substrate or as a host material for diluted magnetic alloying.