Characterization and Active Control of Weyl Semimetals

ended

In the past few years, a new topological phase of matter, the Weyl semimetals, has been discovered. In Weyl semimetals, the bulk band structure is characterized by pairs of Weyls cones with opposite chirality that are separated in momentum space, resembling graphene. Its non-trivial electronic structure leads to quantum anomalies and unique transport properties including an extremely high mobility, which offers not only a platform for testing relativistic theories but also a great potential for device applications. The combination of bulk-transport and topological protection currently inspires many researchers to seek novel applications of Weyl semimetals in the emerging areas of neuromorphic computing, quantum computing or reversible computing. However, the great promise of Weyl semimetals, or topological material in general, is yet to be unleashed through meaningful demonstrations of their potential in device applications. In this action, we will develop electrically-gated devices to actively control the transport properties of Weyl semimetals at IBM Research - Zurich. More precisely, we will build and test a Weyl semimetal valley filter based on a recent theoretical proposal. To do this, we will first perform extensive material characterizations and magneto-transport measurements on the candidate Weyl semimetal materials to verify sample quality and its influence on the transport properties. Afterward, we will develop the processing steps to fabricate Weyl semimetal field-effect devices with high gate control and allow incorporation of additional contact structures for valley polarization sensing. Being able to actively control the transport properties of Weyl semimetals is not only a crucial step for its application in information technology but also for probing new physics of Weyl fermions. To achieve the objectives, a secondment is planned at Max Planck-Institute for the Chemical Physics of Solids for knowledge transfer and complimentary experiments.