Publications (47)
Topological flat bands in a family of multilayer graphene moiré lattices
Dacen Waters, Ruiheng Su, Ellis Thompson +10
Moiré materials host a wealth of intertwined correlated and topological states of matter, all arising from flat electronic bands with nontrivial quantum geometry. A prominent exam…
Local Spectroscopy of the Electrically Tunable Band Gap in Trilayer Graphene
Matthew Yankowitz, Fenglin Wang, Chun Ning Lau +1
The stacking order degree of freedom in trilayer graphene plays a critical role in determining the existence of an electric field tunable band gap. We present spatially-resolved tu…
Microwave Imaging of Edge Conductivity in Graphene at Charge Neutrality and Quantum Hall States
Hongtao Yan, Chun-Chih Tseng, Anzhuoer Li +8
We report local conductivity imaging of edge states in monolayer graphene by millikelvin microwave impedance microscopy (MIM). At the charge-neutrality point, as the magnetic field…
Evolution of the electronic band structure of twisted bilayer graphene upon doping
Shengqiang Huang, Matthew Yankowitz, Kanokporn Chattrakun +2
The electronic band structure of twisted bilayer graphene develops van Hove singularities whose energy depends on the twist angle between the two layers. Using Raman spectroscopy,…
Dynamic band structure tuning of graphene moiré superlattices with pressure
Matthew Yankowitz, Jeil Jung, Evan Laksono +7
Heterostructures of atomically-thin materials have attracted significant interest owing to their ability to host novel electronic properties fundamentally distinct from their const…
Anomalous metal and superconducting phases in rhombohedral graphene
Anna Okounkova, Abigail Sohm, Tobias Faehndrich +7
The paper investigates gate‑tuned regions in rhombohedral graphene on a WSe₂ substrate that show either zero‑resistance superconductivity or a finite‑resistance “anomalous metal” s…
Unraveling intrinsic flexoelectricity in twisted double bilayer graphene
Yuhao Li, Xiao Wang, Deqi Tang +8
Moiré superlattices of two-dimensional (2D) materials with a small twist angle are thought to exhibit appreciable flexoelectric effect, though unambiguous confirmation of their fl…
Magic Angle Spectroscopy
Alexander Kerelsky, Leo McGilly, Dante M. Kennes +9
The electronic properties of heterostructures of atomically-thin van der Waals (vdW) crystals can be modified substantially by Moiré superlattice potentials arising from an interl…
Visualizing the microscopic origins of topology in twisted molybdenum ditelluride
Ellis Thompson, Keng Tou Chu, Florie Mesple +14
In moiré materials with flat electronic bands and suitable quantum geometry, strong correlations can give rise to novel topological states of matter. The nontrivial band topology…
Electrically tunable correlated and topological states in twisted monolayer-bilayer graphene
Shaowen Chen, Minhao He, Ya-Hui Zhang +8
Twisted van der Waals heterostructures with flat electronic bands have recently emerged as a platform for realizing correlated and topological states with an extraordinary degree o…
Record magnetoresistance, enhanced superconductivity, and fermiology in WTe2
Gianluca Delgado, Elliott Runburg, Chaowei Hu +12
The diverse electronic properties of transition metal chalcogenides can be very sensitive to crystal imperfections. A new crystal growth technique, known as horizontal flux transpo…
Ambipolar Landau levels and strong band-selective carrier interactions in monolayer WSe
Martin V. Gustafsson, Matthew Yankowitz, Carlos Forsythe +6
Monolayers (MLs) of transition metal dichalcogenides (TMDs) exhibit unusual electrical behavior under magnetic fields due to their intrinsic spin-orbit coupling and lack of inversi…
Symmetry-broken Chern insulators in twisted double bilayer graphene
Minhao He, Jiaqi Cai, Ya-Hui Zhang +7
Twisted double bilayer graphene (tDBG) has emerged as an especially rich platform for studying strongly correlated and topological states of matter. The material features moiré ba…
Band Structure Mapping of Bilayer Graphene via Quasiparticle Scattering
Matthew Yankowitz, Joel I-Jan Wang, Suchun Li +7
A perpendicular electric field breaks the layer symmetry of Bernal-stacked bilayer graphene, resulting in the opening of a band gap and a modification of the effective mass of the…
Gate-tunable proximity effects in graphene on layered magnetic insulators
Chun-Chih Tseng, Tiancheng Song, Qianni Jiang +11
The extreme versatility of two-dimensional van der Waals (vdW) materials derives from their ability to exhibit new electronic properties when assembled in proximity with dissimilar…
Continuously tunable uniaxial strain control of van der Waals heterostructure devices
Zhaoyu Liu, Xuetao Ma, John Cenker +13
Uniaxial strain has been widely used as a powerful tool for investigating and controlling the properties of quantum materials. However, existing strain techniques have so far mostl…
Valleytronics in 2D Materials Roadmap
Kyle L. Seyler, Giancarlo Soavi, Bent Weber +30
Valleytronics exploits non-equivalent energy extrema in the electronic band structure of crystalline solids -- the valley degree of freedom -- to encode, manipulate, and read out i…
Topological electronic crystals in twisted bilayer-trilayer graphene
Ruiheng Su, Dacen Waters, Boran Zhou +5
In a dilute two-dimensional electron gas, Coulomb interactions can stabilize the formation of a Wigner crystal. Although Wigner crystals are topologically trivial, it has been pred…
Emergence of Superlattice Dirac Points in Graphene on Hexagonal Boron Nitride
Matthew Yankowitz, Jiamin Xue, Daniel Cormode +6
The Schrödinger equation dictates that the propagation of nearly free electrons through a weak periodic potential results in the opening of band gaps near points of the reciprocal…
Switching 2D Magnetic States via Pressure Tuning of Layer Stacking
Tiancheng Song, Zaiyao Fei, Matthew Yankowitz +15
The physical properties of two-dimensional van der Waals (2D vdW) crystals depend sensitively on the interlayer coupling, which is intimately connected to the stacking arrangement…
Graphene on Hexagonal Boron Nitride
Matthew Yankowitz, Jiamin Xue, Brian J. LeRoy
The field of graphene research has developed rapidly since its first isolation by mechanical exfoliation in 2004. Due to the relativistic Dirac nature of its charge carriers, graph…
Sliding Disassembly of van der Waals Heterostructures
Jordan Pack, Karl V. Falb, Sanat Ghosh +13
Many recent advances in our understanding of two-dimensional (2D) electron systems stem from van der Waals (vdW) heterostructures. The assembly process relies on the weak bonding a…
Abrupt switching of the anomalous Hall effect by field-rotation in nonmagnetic ZrTe5
Joshua Mutch, Xuetao Ma, Chong Wang +7
The Hall effect arises when time reversal symmetry is broken by either intrinsic magnetism or an external magnetic field. The latter contribution dominates in non-magnetic material…
Low-lying Electronic Structure of Rare-Earth Based Topological Nodal Line Semimetal Candidate DySbTe
Nathan Valadez, Iftakhar Bin Elius, Dante James +11
Lanthanide (Ln) based LnSbTe materials have garnered significant attention due to rich interplay of long range magnetic ordering and topological properties, driven by unique crysta…
Pervasive spin-triplet superconductivity in rhombohedral graphene
Manish Kumar, Derek Waleffe, Anna Okounkova +6
Magnetic fields typically suppress superconductivity once the Zeeman energy exceeds the pairing gap, unless mechanisms such as unconventional pairing, strong spin-orbit coupling, o…
Anomalous Hall effect at half filling in twisted bilayer graphene
Chun-Chih Tseng, Xuetao Ma, Zhaoyu Liu +4
Magic-angle twisted bilayer graphene (tBLG) has been studied extensively owing to its wealth of symmetry-broken phases, correlated Chern insulators, orbital magnetism, and supercon…
Unusual magnetotransport in twisted bilayer graphene
Joe Finney, Aaron L. Sharpe, Eli J. Fox +10
We present transport measurements of bilayer graphene with 1.38° interlayer twist and apparent additional alignment to its hexagonal boron nitride cladding. As with other devices…
Giant elastoresistance in magic-angle twisted bilayer graphene
Xuetao Ma, Zhaoyu Liu, Jiaqi Cai +5
Strongly correlated and topological phases in moiré materials are exquisitely sensitive to lattice geometry at both atomic and superlattice length scales. Twist angle, pressure, a…
The 2D Materials Roadmap
Wencai Ren, Peter Bøggild, Joan Redwing +70
Over the past two decades, 2D materials have rapidly evolved into a diverse and expanding family of material platforms. Many members of this materials class have demonstrated their…
Competing correlated states and abundant orbital magnetism in twisted monolayer-bilayer graphene
Minhao He, Ya-Hui Zhang, Yuhao Li +5
Flat band moiré superlattices have recently emerged as unique platforms for investigating the interplay between strong electronic correlations, nontrivial band topology, and multi…
Strongly interacting Hofstadter states in magic-angle twisted bilayer graphene
Minhao He, Xiaoyu Wang, Jiaqi Cai +8
Magic-angle twisted bilayer graphene (MATBG) hosts a multitude of strongly correlated states at partial fillings of its flat bands. In a magnetic field, these flat bands further ev…
Pressure-induced commensurate stacking of graphene on boron nitride
Matthew Yankowitz, K. Watanabe, T. Taniguchi +2
Combining atomically-thin van der Waals materials into heterostructures provides a powerful path towards the creation of designer electronic devices. The interaction strength betwe…
Interplay of electronic crystals with integer and fractional Chern insulators in moiré pentalayer graphene
Dacen Waters, Anna Okounkova, Ruiheng Su +8
The rapid development of moiré quantum matter has recently led to the remarkable discovery of the fractional quantum anomalous Hall effect, and sparked predictions of other novel…
Dynamically tunable moiré Rydberg excitons in a monolayer semiconductor on twisted bilayer graphene
Minhao He, Jiaqi Cai, Huiyuan Zheng +8
Moiré excitons are emergent optical excitations in 2D semiconductors with deep moiré superlattice potentials. While these excitations have been realized in several platforms, a s…
Single-gate tracking behavior in flat-band multilayer graphene devices
KryÅ¡tof KoláÅ, Dacen Waters, Joshua Folk +2
A central feature of many van der Waals (vdW) materials is the ability to precisely control their charge doping, , and electric displacement field, , using top and bottom gat…
Intrinsic disorder in graphene on transition metal dichalcogenide heterostructures
Matthew Yankowitz, Stefano Larentis, Kyounghwan Kim +8
The electronic properties of two-dimensional materials such as graphene are extremely sensitive to their environment, especially the underlying substrate. Planar van der Waals bond…
Electronic interactions in Dirac fluids visualized by nano-terahertz spacetime interference of electron-photon quasiparticles
Suheng Xu, Yutao Li, Rocco A. Vitalone +15
Ultraclean graphene at charge neutrality hosts a quantum critical Dirac fluid of interacting electrons and holes. Interactions profoundly affect the charge dynamics of graphene, wh…
Observing the Birth of Rydberg Exciton Fermi Polarons on a Moire Fermi Sea
Eric A. Arsenault, Gillian E. Minarik, Jiaqi Cai +8
The optical spectra of two-dimensional (2D) semiconductors are dominated by tightly bound excitons and trions. In the low doping limit, trions are often described as three-body qua…
Electric Field Control of Soliton Motion and Stacking in Trilayer Graphene
Matthew Yankowitz, Joel I-Jan Wang, A. Glen Birdwell +7
The crystal structure of a material plays an important role in determining its electronic properties. Changing from one crystal structure to another involves a phase transition whi…
Mixed-dimensional moiré systems of graphitic thin films with a twisted interface
Dacen Waters, Ellis Thompson, Esmeralda Arreguin-Martinez +7
Moiré patterns formed by stacking atomically-thin van der Waals crystals with a relative twist angle can give rise to dramatic new physical properties. The study of moiré materia…
Tunable crystal symmetry in graphene-boron nitride heterostructures with coexisting moiré superlattices
Nathan R. Finney, Matthew Yankowitz, Lithurshanaa Muraleetharan +4
In heterostructures consisting of atomically thin crystals layered on top of one another, lattice mismatch or rotation between the layers results in long-wavelength moiré superlat…
Local Spectroscopic Characterization of Spin and Layer Polarization in WSe
Matthew Yankowitz, Devin McKenzie, Brian J. LeRoy
We report scanning tunneling microscopy (STM) and spectroscopy (STS) measurements of monolayer and bilayer WSe. We measure a band gap of 2.21 0.08 eV in monolayer WSe…
Observation of momentum dependent charge density wave gap in EuTe4
Iftakhar Bin Elius, Nathan Valadez, Gyanendra Dhakal +10
The occurrence of charge density wave (CDW) phenomena, particularly in low dimensional rare-earth chalcogenides, has attracted substantial research interest. Among these materials,…
On the origin of anomalous hysteresis in graphite/boron nitride transistors
Dacen Waters, Derek Waleffe, Ellis Thompson +9
Field-effect devices constructed by stacking flakes of van der Waals (vdW) materials, with hexagonal boron nitride (hBN) playing the role of gate dielectric, often exhibit virtuall…
Superconductivity from dual-surface carriers in rhombohedral graphene
Manish Kumar, Derek Waleffe, Anna Okounkova +7
Intrinsic rhombohedral graphene hosts an unusual low-energy electronic wavefunction, predominantly localized at its outer crystal faces with negligible presence in the bulk. Increa…
Tunable correlation-driven symmetry breaking in twisted double bilayer graphene
Minhao He, Yuhao Li, Jiaqi Cai +5
A variety of correlated phases have recently emerged in select twisted van der Waals (vdW) heterostructures owing to their flat electronic dispersions. In particular, heterostructu…
Tuning superconductivity in twisted bilayer graphene
Matthew Yankowitz, Shaowen Chen, Hryhoriy Polshyn +5
Materials with flat electronic bands often exhibit exotic quantum phenomena owing to strong correlations. Remarkably, an isolated low-energy flat band can be induced in bilayer gra…