2026 APS global summit talks from our group.
Quasiparticle microscope at single quantum hall impurities
Wed. March 18, 12:48 — 1:00 p.m.
Convention Center,Meeting Room 405
Presenter: Yiming Sun
Part of MAR-M35 STM and NanoSQUID Imaging of Layered Graphene Structures
Quantum Hall systems host highly correlated and degenerate electronic states, where exotic quasiparticles such as fractionalized anyons can emerge. However, conventional bulk measurements lack the spatial resolution to probe them individually. Using scanning tunneling spectroscopy (STS) on an ultraclean graphene device under a high magnetic field, we directly visualize quantum Hall quasiparticles in real space near single charged defects. The Coulomb potential of these defects lifts the Landau-level degeneracy, separating orbits with different angular momentum in energy and thereby enabling their individual imaging. When quasiparticles are bound to the impurity potential, distinct spectral features arise, encoding the number and type of bound states. By analyzing the spectral weight, we visualize localized quasiparticles in real space—realizing a quasiparticle microscope that reveals their distribution down to the single-defect limit and opens a pathway to observe and manipulate non-Abelian anyons.
Superconductivity and Ferroelectric Orbital Magnetism in Semimetallic Rhombohedral Hexalayer Graphene
Tue. March 17, 12:36 — 12:48 p.m.
Convention Center,Meeting Room 201
Presenter: Jinghao Deng
Part of MAR-G24 Novel Superconductivity in Two-Dimensional Systems
Rhombohedral multilayer graphene has emerged as a promising platform for exploring correlated and topological quantum phases, enabled by its Berry-curvature-bearing flat bands. While prior work has focused on separated conduction and valence bands, we probe the extensive semimetallic regime of rhombohedral hexalayer graphene. We survey a rich phase diagram dominated by flavor-symmetry breaking and reveal an electric-field-driven band inversion through fermiology. Near this inversion, we find a superconducting-like state confined to a region with emergent electron and hole Fermi surfaces. In addition, two multiferroic orbital-magnetic phases are observed: a ferrovalley state near zero field and a ferroelectric state at large fields around charge neutrality. The latter shows electric-field-reversible magnetic hysteresis, consistent with a ΔP·M multiferroic order parameter.
Signatures of tunable magnetic-field-induced superconductivity and their large Pauli violation in hexalayer rhombohedral graphene
Tue. March 17, 12:48 — 1:00 p.m.
Convention Center,Meeting Room 201
Presenter: Jiabin Xie
Part of MAR-G24 Novel Superconductivity in Two-Dimensional Systems
Rhombohedral multilayer graphene systems have emerged as a unique platform to host multiple unconventional superconducting behaviors. Here, we report signatures of in-plane magnetic fields induced superconductivity in hexalayer rhombohedral graphene near a symmetry-breaking transition. The onset and critical magnetic field for the field-induced superconductivity can be continuously tuned by electric fields with a critical magnetic field maxima > 14 T which is far beyond the Pauli limit. Fermiology analysis reveals that these superconducting states derived from the Lifshitz transition at the symmetry breaking phase boundary. The experimental results suggest a highly unconventional superconductivity behavior in hexalayer rhombohedral graphene that possibly possesses a spin-triplet order parameter.
