Molten salt-directed catalytic synthesis of room-temperature ferromagnetic transition-metal nitride nanosheets

TL;DR

A new method creates ultrathin molybdenum nitride nanosheets that show strong magnetism at room temperature, promising for future electronic devices.

Contribution

A three-step molten salt-directed catalytic method to synthesize intrinsic room-temperature ferromagnetic γ-Mo2N nanosheets.

Findings

γ-Mo2N nanosheets show ferromagnetism with a Curie temperature of about 360 K.

Ferromagnetism is attributed to 4d electrons of Mo atoms with itinerant characteristics.

Extensive characterization confirms structural stability and absence of magnetic impurities.

Abstract

The next generation of low-power electronic/spintronic devices based on two-dimensional (2D) magnetic materials has great application prospects. However, so far, the numbers of intrinsic room-temperature magnetic 2D materials is limited. Here, we report a simple and effective three-step molten salt-directed catalytic method for obtaining intrinsic room-temperature ferromagnetic gamma-Mo2N (γ-Mo2N) nanosheets. The γ-Mo2N nanosheets with high crystallization and ultra-thin 2D layered structure characteristics show obvious ferromagnetism and Curie temperature (Tc) up to about 360 K. Meanwhile, ICP-AES measurement excludes the possibility of ferromagnetic impurities. Extensive synchrotron radiation X-ray absorption fine structure (XAFS) spectra characterizations confirm the bonding configuration of Mo–N coordination around Mo atoms as well as the structural stability of the samples. Detailed spin-polarized density functional theory (DFT) calculations reveal that ferromagnetism of γ-Mo2N nanosheets is mainly contributed by 4d electrons of Mo atoms with itinerant electron characteristics. This work highlights γ-Mo2N nanosheets as a promising intrinsic room-temperature ferromagnetic material for the development of spintronics or spin-based electronics.

We report a facile molten-salt strategy to synthesize ultrathin γ-Mo2N nanosheets, which exhibit intrinsic room-temperature ferromagnetism. This work establishes transition metal nitrides as a new class of 2D magnetic materials for spintronics.

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