ABSTRACT
Interlayer decoupling plays an essential role in realizing unprecedented properties in atomically thin materials, but it remains relatively unexplored in the bulk. It is unclear how to realize a large crystal that behaves as its monolayer counterpart by artificial manipulation. Here, we construct a superlattice consisting of alternating layers of NbSe2 and highly porous hydroxide, as a proof of principle for realizing interlayer decoupling in bulk materials. In (NaOH)0.5NbSe2, the electric decoupling is manifested by an ideal 1D insulating state along the interlayer direction. Vibration decoupling is demonstrated through the absence of interlayer models in the Raman spectrum, dominant local modes in heat capacity, low interlayer coupling energy and out-of-plane thermal conductivity (0.28 W/mK at RT) that are reduced to a few percent of NbSe2's. Consequently, a drastic enhancement of CDW transition temperature (>110 K) and Pauling-breaking 2D superconductivity is observed, suggesting that the bulk crystal behaves similarly to an exfoliated NbSe2 monolayer. Our findings provide a route to achieve intrinsic 2D properties on a large-scale without exfoliation.
ABSTRACT
Transition metal dichalcogenides (TMDs) have attracted intensive research interest due to their diverse properties. However, ferromagnetism is not observed in layered TMDs, except for monolayer VSe2. In this study, we report the synthesis of a bulk ferromagnetic material (LiOH)0.1VS2 based on topochemical reactions. The results demonstrate that the (LiOH)0.1VS2 crystal exhibits strong anisotropic ferromagnetism below a critical temperature of 40 K. Calculations uncover that the in-plane strains in a VS2 superlattice can induce large magnetic anisotropic energy, which stabilizes the long-range ferromagnetic order. The findings provide a new approach to induce ferromagnetism in bulk TMD materials.
