
2024 James Clerk Maxwell Medal and Prize
Dr Frank Schindler for numerous conceptual contributions to condensed matter physics; in particular, the prediction of higher-order topological insulators, novel quantum materials whose lossless edge states promise energy-efficient microelectronics in the post-silicon age.
Dr Frank Schindler’s work in theoretical condensed matter physics has ushered in a new era of topological materials. By combining concepts from quantum physics and the mathematical field of topology, his theoretical models have revealed a novel class of materials, known as higher-order topological insulators (HOTIs), which are characterised by their unusual electronic properties. Unlike previous topological insulators with conducting surface states, HOTIs conduct current only along their hinges, making them especially resilient to impurities and disorder within the crystal. Their hinge states allow for resistance-free electron flow and could power energy-efficient electronic devices. In addition to their role in the development of post-silicon hardware, HOTIs are seen as potential components for future quantum computers.
Besides his conceptual work, Schindler has confirmed that HOTIs appear in natural materials: together with experimentalists, he demonstrated that elementary bismuth hosts a higher-order topological phase. Schindler’s foundational work in this area began a flurry of subsequent and ongoing research focusing on the properties, detection methods and material realisations of HOTIs. This effort concentrates not only on natural materials like bismuth bromide, but also revolves around metamaterial platforms such as photonic crystals that can stabilise lossless hinge states made of light. In 2023, Schindler was invited to present his pioneering work in a keynote talk headlining a session on HOTIs at the March Meeting of the American Physical Society, the largest physics conference worldwide.
After three years of postdoctoral research at Princeton University, Schindler was appointed to a lectureship at Imperial College London in 2023. He has authored more than 30 research articles on a diverse range of topics that goes well beyond HOTIs. For example, his recent research has much improved our physical understanding of non-Hermitian topological phases, which represent a new paradigm for non-equilibrium phases of matter. Moreover, he has co-authored influential papers on flat-band materials such as twisted bilayer graphene, another recent focal point of condensed matter physics. Further prominent themes of Schindler’s research are topological superconductors, machine learning applied to condensed matter problems, and non-thermalising quantum systems.
Notwithstanding the breadth of his research, topological insulators remain Schindler’s primary interest: in early 2024, he and experimental collaborators confirmed elementary arsenic as the first hybrid topological insulator material. This state merges the features of conventional topological insulators and HOTIs to give rise to unique electronic properties and lossless conductance along surface step edges instead of hinges.