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1. Quantum Hall–based superconducting interference device

   https://doi.org/10.1126/sciadv.aaw8693  

   Seredinski, Andrew; Draelos, Anne W.; Arnault, Ethan G.; Wei, Ming-Tso; Li, Hengming; Fleming, Tate; Watanabe, Kenji; Taniguchi, Takashi; Amet, François; Finkelstein, Gleb (September 2019, Science Advances)

   We present a study of a graphene-based Josephson junction with dedicated side gates carved from the same sheet of graphene as the junction itself. These side gates are highly efficient and allow us to modulate carrier density along either edge of the junction in a wide range. In particular, in magnetic fields in the 1- to 2-T range, we are able to populate the next Landau level, resulting in Hall plateaus with conductance that differs from the bulk filling factor. When counter-propagating quantum Hall edge states are introduced along either edge, we observe a supercurrent localized along that edge of the junction. Here, we study these supercurrents as a function of magnetic field and carrier density. 

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2. Supercurrent in Graphene Josephson Junctions with Narrow Trenches in the Quantum Hall Regime

   https://doi.org/10.1557/adv.2018.469  

   Seredinski, Andrew; Draelos, Anne; Wei, Ming-Tso; Ke, Chung-Ting; Fleming, Tate; Mehta, Yash; Mancil, Ethan; Li, Hengming; Taniguchi, Takashi; Watanabe, Kenji; et al (April 2018, MRS Advances)

   ABSTRACT Coupling superconductors to quantum Hall edge states is the subject of intense investigation as part of the ongoing search for non-abelian excitations. Our group has previously observed supercurrents of hundreds of picoamperes in graphene Josephson junctions in the quantum Hall regime. One of the explanations of this phenomenon involves the coupling of an electron edge state on one side of the junction to a hole edge state on the opposite side. In our previous samples, these states are separated by several microns. Here, a narrow trench perpendicular to the contacts creates counterpropagating quantum Hall edge channels tens of nanometres from each other. Transport measurements demonstrate a change in the low-field Fraunhofer interference pattern for trench devices and show a supercurrent in both trench and reference junctions in the quantum Hall regime. The trench junctions show no enhancement of quantum Hall supercurrent and an unexpected supercurrent periodicity with applied field, suggesting the need for further optimization of device parameters. 

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3. Discovery of an Intrinsic Antiferromagnetic Semiconductor EuSc ₂ Te ₄ With Magnetism‐Driven Nonlinear Transport

   https://doi.org/10.1002/adfm.202424231  

   Lee, Seng Huat; Zhao, Yufei; Gluscevich, Noble; Yi, Hemian; Morgan, Zachary; Cao, Huibo; Koo, Jahyun; Wang, Yu; He, Jingyang; Gopalan, Venkatraman; et al (March 2025, Advanced Functional Materials)

   Abstract Magnetic topological materials have recently emerged as a promising platform for studying quantum geometry by the nonlinear transport in thin film devices. In this work, an antiferromagnetic (AFM) semiconductor EuSc₂Te₄ as the first bulk crystal that exhibits quantum geometry‐driven nonlinear transport is reported. This material crystallizes into an orthorhombic lattice with AFM order below 5.2 K and a bandgap of less than 50 meV. The calculated band structure aligns with the angle‐resolved photoemission spectroscopy spectrum. The AFM order preserves combined space‐time inversion symmetry but breaks both spatial inversion and time‐reversal symmetry, leading to the nonlinear Hall effect (NLHE). Nonlinear Hall voltage measured in bulk crystals appears at zero field, peaks near the spin‐flop transition as the field increases, and then diminishes as the spin moments align into a ferromagnetic order. This field dependence, along with the scaling analysis of the nonlinear Hall conductivity, suggests that the NLHE of EuSc₂Te₄ involves contributions from quantum metric, in addition to extrinsic contributions, such as spin scattering and junction effects. Furthermore, this NLHE is found to have the functionality of broadband frequency mixing, indicating its potential applications in electronics. This work reveals a new avenue for studying magnetism‐induced nonlinear transport in magnetic materials. 

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4. Yang-Mills flows for multilayered graphene

   https://doi.org/10.1007/JHEP08(2025)114  

   Iugov, Vasilii; Nekrasov, Nikita (August 2025, Journal of High Energy Physics)

   A<sc>bstract</sc> We clarify the origin of magic angles in twisted multilayered graphene using Yang-Mills flows in two dimensions. We relate the effective Hamiltonian describing the electrons in the multilayered graphene to the$$ {\overline{\partial}}_A $$ ${\overline{\partial }}_A$ operator on a two dimensional torus coupled to an SU(N) gauge field. Despite the absence of a characteristic class such asc₁relevant for the quantum Hall effect, we show that there are topological invariants associated with the zero modes occuring in a family of Hamiltonians. The flatbands in the spectrum of the effective Hamiltonian are associated with Yang-Mills connections, studied by M. Atiyah and R. Bott long time ago. The emergent U(1) magnetic field with nonzero flux is presumably responsible for the observed Hall effect in the absence of (external) magnetic field. We provide a numeric algorithm transforming the original single-particle Hamiltonian to the direct sum of$$ {\overline{\partial}}_A $$ ${\overline{\partial }}_A$ operators coupled to abelian gauge fields with non-zeroc₁’s. Our gradient flow perspective gives a simple bound for magic angles: if the gauge fieldA(α) is such that the YM energy$$ {\int}_{{\mathbbm{T}}^2} $$ ${\int }_{T^2}$ tr$$ {F}_{A\left(\alpha \right)}^2 $$ $F_{A\left(\alpha \right)}^2$ is smaller than that of U(1) magnetic flux embedded into SU(2), thenαis not magic. 

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5. Large thermal Hall effect in MnPS ₃

   https://doi.org/10.1088/1361-6633/adf916  

   Nawwar, Mohamed; Neumann, Robin R; Wen, Jiamin; Mertig, Ingrid; Mook, Alexander; Heremans, Joseph P (August 2025, Reports on Progress in Physics)

   Abstract Recent studies have demonstrated that the thermal Hall effect (THE) can originate from magnons (magnon Hall effect), phonons (phonon Hall effect), or their combination (magnon–polaron Hall effect). The magnon–polaron Hall effect, first observed in Fe₂Mo₃O₈, is particularly intriguing as its thermal Hall signal can be remarkably large. In this study, we explore the THE in MnPS₃, an insulating antiferromagnetic material exhibiting a spin-flop (SF) transition and significant magnetoelastic coupling, making it a strong candidate for studying the THE originating from spin–lattice coupling. We report an exceptionally large thermal Hall angle down to 4 K and show that it cannot be accounted for by standard calculations based on the intrinsic magnon–polaron Berry curvature. Our findings provide an in-depth analysis of the role of the SF transition in the thermal properties of MnPS₃and call for further theory development on magnon–phonon coupling and scattering to reveal their influence on transverse heat transport. 

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