Vacancy-Induced Ferromagnetism of MoS₂ Nanosheets

TLDR

Two‑dimensional ultrathin semiconductor nanosheets are sought for their outstanding magnetic properties. The study proposes a phase‑incorporation strategy to induce robust room‑temperature ferromagnetism in nonmagnetic MoS₂. A two‑step hydrothermal process introduces sulfur vacancies in 2H‑MoS₂ nanosheets, converting local lattice to 1T‑MoS₂ and enabling phase incorporation. 25 % 1T‑MoS₂ phase incorporation in 2H‑MoS₂ nanosheets increases electron carrier concentration by an order of magnitude, introduces a Mo⁴⁺ 4d band‑gap state, and yields a robust intrinsic ferromagnetic response of 0.25 μB/Mo at room temperature, demonstrating a new route to manipulate exchange interactions in 2D nanostructures.

Abstract

Outstanding magnetic properties are highly desired for two-dimensional ultrathin semiconductor nanosheets. Here, we propose a phase incorporation strategy to induce robust room-temperature ferromagnetism in a nonmagnetic MoS2 semiconductor. A two-step hydrothermal method was used to intentionally introduce sulfur vacancies in a 2H-MoS2 ultrathin nanosheet host, which prompts the transformation of the surrounding 2H-MoS2 local lattice into a trigonal (1T-MoS2) phase. 25% 1T-MoS2 phase incorporation in 2H-MoS2 nanosheets can enhance the electron carrier concentration by an order, introduce a Mo4+ 4d energy state within the bandgap, and create a robust intrinsic ferromagnetic response of 0.25 μB/Mo by the exchange interactions between sulfur vacancy and the Mo4+ 4d bandgap state at room temperature. This design opens up new possibility for effective manipulation of exchange interactions in two-dimensional nanostructures.