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Abstract The electrochemical intercalation is one of most powerful tools for tuning the intrinsic properties of quasi-two-dimensional (2D) materials. In this work, ionic organic cations, $$[\\hbox {C}_2\\hbox {MIm}]^+$$ and $$\\hbox {[DEMB]}^+$$ , are successfully intercalated into $$\\hbox {NiPS}_3$$ interlayer via electrochemical intercalation. The both $$[\\hbox {C}_2\\hbox {MIm}]^+$$ and $$\\hbox {[DEMB]}^+$$ intercalated $$\\hbox {NiPS}_3$$ samples show ferrimagnetic transition with the transition temperature of 65 K and 85 K, respectively. Raman spectroscopy, X-ray photoelectron spectroscopy and Hall measurements reveal that the electron doping and sulfur vacancies created by the cation intercalation play important role in the ferrimagnetic transition. Our work provides a new pathway to manipulation of magnetism in layered 2D materials.

Reducing the dimensionality of layered materials can result in properties distinct from their bulk crystals 1 – 3 . However, the emergent properties in atomically thin samples, in particular in metallic monolayer flakes, are often obtained at the expense of other important properties. For example, while Ising superconductivity—where the pairing of electrons with opposite out-of-plane spins from K and K′ valleys leads to an in-plane upper critical field exceeding the Pauli limit—does not occur in bulk NbSe 2 , it was observed in two-dimensional monolayer flakes 4 . However, the critical temperature was reduced as compared to bulk crystals 4 – 13 . Here we take a different route to control the superconducting properties of NbSe 2 by intercalating bulk crystals with cations from ionic liquids. This produces Ising superconductivity with a similar critical temperature to the non-intercalated bulk and is more stable than in a monolayer flake. Our angle-resolved photoemission spectroscopy measurements reveal the effectively two-dimensional electronic structure, and a comparison of the experimental electronic structures between intercalated bulk NbSe 2 and monolayer NbSe 2 film reveals that the intercalant induces electron doping. This suggests ionic liquid cation intercalation is an effective technique for controlling both the dimensionality and the carrier concentration, allowing tailored properties exceeding both bulk crystals and monolayer samples. The superconducting critical temperature of monolayer materials is often lower than their bulk counterparts. Now, intercalation is shown to induce two-dimensional superconducting properties while maintaining the bulk critical temperature.

The electrochemical intercalation is one of most powerful tools for tuning the intrinsic properties of quasi-two-dimensional (2D) materials. In this work, ionic organic cations, [Formula: see text] and [Formula: see text], are successfully intercalated into [Formula: see text] interlayer via electrochemical intercalation. The both [Formula: see text] and [Formula: see text] intercalated [Formula: see text] samples show ferrimagnetic transition with the transition temperature of 65 K and 85 K, respectively. Raman spectroscopy, X-ray photoelectron spectroscopy and Hall measurements reveal that the electron doping and sulfur vacancies created by the cation intercalation play important role in the ferrimagnetic transition. Our work provides a new pathway to manipulation of magnetism in layered 2D materials.The electrochemical intercalation is one of most powerful tools for tuning the intrinsic properties of quasi-two-dimensional (2D) materials. In this work, ionic organic cations, [Formula: see text] and [Formula: see text], are successfully intercalated into [Formula: see text] interlayer via electrochemical intercalation. The both [Formula: see text] and [Formula: see text] intercalated [Formula: see text] samples show ferrimagnetic transition with the transition temperature of 65 K and 85 K, respectively. Raman spectroscopy, X-ray photoelectron spectroscopy and Hall measurements reveal that the electron doping and sulfur vacancies created by the cation intercalation play important role in the ferrimagnetic transition. Our work provides a new pathway to manipulation of magnetism in layered 2D materials.

The electrochemical intercalation is one of most powerful tools for tuning the intrinsic properties of quasi-two-dimensional (2D) materials. In this work, ionic organic cations, and , are successfully intercalated into interlayer via electrochemical intercalation. The both and intercalated samples show ferrimagnetic transition with the transition temperature of 65 K and 85 K, respectively. Raman spectroscopy, X-ray photoelectron spectroscopy and Hall measurements reveal that the electron doping and sulfur vacancies created by the cation intercalation play important role in the ferrimagnetic transition. Our work provides a new pathway to manipulation of magnetism in layered 2D materials.

The electrochemical intercalation is one of most powerful tools for tuning the intrinsic properties of quasi-two-dimensional (2D) materials. In this work, ionic organic cations, $$[\\hbox {C}_2\\hbox {MIm}]^+$$ and $$\\hbox {[DEMB]}^+$$ , are successfully intercalated into $$\\hbox {NiPS}_3$$ interlayer via electrochemical intercalation. The both $$[\\hbox {C}_2\\hbox {MIm}]^+$$ and $$\\hbox {[DEMB]}^+$$ intercalated $$\\hbox {NiPS}_3$$ samples show ferrimagnetic transition with the transition temperature of 65 K and 85 K, respectively. Raman spectroscopy, X-ray photoelectron spectroscopy and Hall measurements reveal that the electron doping and sulfur vacancies created by the cation intercalation play important role in the ferrimagnetic transition. Our work provides a new pathway to manipulation of magnetism in layered 2D materials.

The electrochemical intercalation is one of most powerful tools for tuning the intrinsic properties of quasi-two-dimensional (2D) materials. In this work, ionic organic cations, and , are successfully intercalated into interlayer via electrochemical intercalation. The both and intercalated samples show ferrimagnetic transition with the transition temperature of 65 K and 85 K, respectively. Raman spectroscopy, X-ray photoelectron spectroscopy and Hall measurements reveal that the electron doping and sulfur vacancies created by the cation intercalation play important role in the ferrimagnetic transition. Our work provides a new pathway to manipulation of magnetism in layered 2D materials.

Van der Waals superlattices are important for tailoring the electronic structures and properties of layered materials. Here we report the superconducting properties and electronic structure of a natural van der Waals superlattice (PbSe)\\(_{1.14}\\)NbSe\\(_2\\). Anisotropic superconductivity with a transition temperature \\(T_c\\) = 5.6 \\(\\pm\\) 0.1 K, which is higher than monolayer NbSe\\(_2\\), is revealed by transport measurements on high-quality samples. Angle-resolved photoemission spectroscopy (ARPES) measurements reveal the two-dimensional electronic structure and a charge transfer of 0.43 electrons per NbSe\\(_2\\) unit cell from the blocking PbSe layer. In addition, polarization-dependent ARPES measurements reveal a significant circular dichroism with opposite contrast at K and K' valleys, suggesting a significant spin-orbital coupling and distinct orbital angular momentum. Our work suggests natural van der Waals superlattice as an effective pathway for achieving intriguing properties distinct from both the bulk and monolayer samples.

Inducing or enhancing superconductivity in topological materials is an important route toward topological superconductivity. Reducing the thickness of transition metal dichalcogenides (e.g. WTe2 and MoTe2) has provided an important pathway to engineer superconductivity in topological matters; for instance, emergent superconductivity with Tc=0.82 K was observed in monolayer WTe2 which also hosts intriguing quantum spin Hall effect, although the bulk crystal is nonsuperconducting. However, such monolayer sample is difficult to obtain, unstable in air, and with extremely low Tc, which could pose a grand challenge for practical applications. Here we report an experimentally convenient approach to control the interlayer coupling to achieve tailored topological properties, enhanced superconductivity and good sample stability through organic cation intercalation of the Weyl semimetals MoTe2 and WTe2. The as-formed organic-inorganic hybrid crystals are weak topological insulators with enhanced Tc of 7.0 K for intercalated MoTe2 (0.25 K for pristine crystal) and 2.3 K for intercalated WTe2 (2.8 times compared to monolayer WTe2). Such organic-cationintercalation method can be readily applied to many other layered crystals, providing a new pathway for manipulating their electronic, topological and superconducting properties.