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Quantum materials provide a powerful platform for realizing emergent phases of matter. Among them, 2D quantum materials and their van der Waals heterostructures create an especially versatile landscape for hosting quantum states beyond those found in conventional bulk materials. In addition, external tuning parameters, such as layer thickness, carrier density, displacement field, strain, and moiré periodicity, expand the accessible parameter space for modulating these quantum phases.
Expanding the 2D Materials Library
Expanding the 2D Materials Library
Access to high-quality ultrathin samples is the first step toward studying quantum phenomena in 2D materials. Although many layered materials beyond graphene and transition metal dichalcogenides (TMDs) can now be synthesized as bulk crystals, reliably isolating clean atomically thin layers from them remains a long-standing challenge in the field, particularly for those with relatively strong interlayer bonding.
Our group develops exfoliation and nanofabrication methods to access these materials beyond conventional approaches. One example is an Al2O3-assisted exfoliation technique, which uses an insulating Al2O3 layer to enhance adhesion to layered crystal surfaces and substantially increase the yield of high-quality monolayer and few-layer samples. This approach is compatible with quantum transport measurements and has enabled studies of fragile quantum states in ultrathin materials, including Fe3GeTe2 and MnBi2Te4. This method has also been widely used to exfoliate a broad range of layered materials, while we continue to develop new approaches for preparing emerging 2D quantum materials.
Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe3GeTe2, Nature 563, 94 (2018).
Tunable Magnetism in 2D Materials
Tunable Magnetism in 2D Materials
2D magnetic materials provide a unique platform for exploring magnetism in the atomically thin limit. Achieving robust and tunable magnetism in these ultrathin crystals, especially near or above room temperature, remains an important goal for both fundamental physics and spintronic applications.
Our group studies magnetic quantum materials by combining ultrathin sample preparation, device fabrication, and external tuning techniques. In previous work, we used the Al2O3-assisted exfoliation method to isolate high-quality Fe3GeTe2 thin flakes and demonstrated stable ferromagnetism down to monolayer. By further using ionic gating to tune carrier density, we realized room-temperature ferromagnetism. These studies establish 2D magnetic materials as a versatile platform for developing low-power spintronic devices.
Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe3GeTe2, Nature 563, 94 (2018).
Topology and Correlation in 2D Materials
Topology and Correlation in 2D Materials
The quantum anomalous Hall (QAH) effect represents a striking example of topology in 2D, where chiral edge transport can emerge without an external magnetic field. Realizing such states in clean, intrinsic material platforms has long been an important goal, and further combining topology with strong electronic correlations opens new opportunities for exploring fractional and interaction-driven quantum phases.
Our group studies topology and correlation through ultrathin device fabrication, quantum transport, and advanced spectroscopic measurements. Representative systems include MnBi2Te4, an intrinsic magnetic topological insulator that hosts QAH states in atomically thin devices, and twisted bilayer MoTe2, a moiré platform for QAH and fractional QAH states, where our momentum-resolved spectroscopy revealed twist-angle-dependent band reconstruction and band flattening near the magic angle. Looking forward, we aim to develop new material platforms and tuning strategies that bring magnetism, topology, correlations, and moiré engineering together to realize controllable quantum phases.
Quantum anomalous Hall effect in intrinsic magnetic topological insulator MnBi2Te4, Science 367, 895 (2020).
Nonmonotonic Band Flattening near the Magic Angle of Twisted Bilayer MoTe2, Phys. Rev. X 15, 041043 (2025).
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