We develop novel soft chemistry approaches to synthesis quantum materials and precisely modulate their properties. By topotactic transformations (e.g. ion intercalation, de-intercalation, and exchange), we achieve precise control over interactions between a material and associated ionic, atomic, or even molecular reservoir.
This strategy significantly broadens the accessible phase space for given material systems. Conceptually, it parallels electrostatic gating in semiconductors, where charge carriers (electrons or holes) modulate material properties; however, in our approach, the active species are ions, atoms, or molecules, allowing for more versatile control mechanisms and even the stabilization of entirely new phases of matter.
Moreover, by incorporating real-time feedback through quantum transport or spectroscopic techniques, we further achieve enhanced control over phase transformations. This strategy opens new possibilities for discovering metastable phases with remarkable properties.
Gate-tunable phase transitions in thin flakes of 1T-TaS2, Nat. Nanotechnol. 10, 270 (2015).
Molecular H2 as the Reducing Agent in Low-Temperature Oxide Reduction Using Metal-Hydrides, J. Am. Chem. Soc. 147, 3032 (2025).
Superconductivity and normal-state transport in compressively strained La2PrNi2O7 thin films, Nat. Mater. 24, 1221 (2025).
Of particular interest, we have applied soft chemistry approaches to explore an expanding family of layered transition metal oxides that exhibit high-temperature superconductivity, particularly cuprates and nickelates. Two contrasting examples illustrate our approaches:
In cuprate BSCCO, we exploit the weak interlayer van der Waals bonding to isolate a two-dimensional layer containing the smallest complete structural unit, enabling the exploration of its intrinsic ground states. Our findings reveal that even at the single-layer limit, cuprates retain all the essential ingredients for high temperature superconductivity.
In Ruddlesden-Popper nickelates, we take advantage of the strong interlayer covalent bonding with the substrate to apply epitaxial compressive strain, successfully stabilizing superconductivity above 40 K at ambient pressure by precisely control of oxygen stoichiometry.
High-temperature superconductivity in monolayer Bi2Sr2CaCu2O8+δ, Nature 575, 156 (2019).
Oscillating paramagnetic Meissner effect and Berezinskii-Kosterlitz-Thouless transition in underdoped Bi2Sr2CaCu2O8+δ, Natl. Sci. Rev. 11, nwad249 (2024).
Signature of ambient pressure superconductivity in thin film La3Ni2O7, Nature 638, 935 (2025).
Van der Waals materials, originally studied in the 1960s and 1970s, have seen a resurgence of interest since the 2010s, driven by the rise of graphene and advances in experimental techniques. Van der Waals materials offer unique advantages for fundamental research due to their atomically thin, layered structures and weak interlayer interactions. These characteristics enable precise control over material composition, thickness, and stacking order, allowing researchers to design and investigate novel quantum phenomena not accessible in conventional bulk materials. Their clean, defect-free surfaces and tunable electronic, optical, and magnetic properties make them ideal platforms for exploring low-dimensional physics, strong correlation effects, and interface-driven phenomena. Furthermore, their compatibility with a wide range of substrates and other 2D materials facilitates the creation of custom heterostructures, opening new avenues for discovery in condensed matter physics and materials science.
We have developed state-of-the-art methods to isolate ultrathin monolayers from bulk crystals while preserving their inherently fragile electronic states that exposes to environment. These monolayers, and their heterostructures, exhibit emergent phenomena that we can access and control through solid-state and soft chemistry approaches.
从二维材料到范德瓦尔斯异质结, 物理 46, 205 (2017), a review article in Chinese.
Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe3GeTe2, Nature 563, 94 (2018).
Quantum anomalous Hall effect in intrinsic magnetic topological insulator MnBi2Te4, Science 367, 895 (2020).