Arthur W. Barnard

Abstract Studies of electronic transport in width-restricted channels of PdCoO2 have recently revealed a novel ‘directional ballistic’ regime, in which ballistic propagation of electrons on an anisotropic Fermi surface breaks the symmetries of bulk transport. Here we introduce a magnetic field to this regime, studying channels of PdCoO2 and PtCoO2 along two crystallographically distinct directions and over a wide range of widths.

Abstract Geometric electron optics may be implemented in solids when electron transport is ballistic on the length scale of a device. Currently, this is realized mainly in 2D materials characterized by circular Fermi surfaces. Here we demonstrate that the nearly perfectly hexagonal Fermi surface of PdCoO2 gives rise to highly directional ballistic transport.

Report Emergent ferromagnetism near three-quarters filling in twisted bilayer graphene Aaron L. Sharpe1,2,*, Eli J. Fox2,3,*, Arthur W. Barnard3, Joe Finney3, Kenji Watanabe4, Takashi Taniguchi4, M. A. Kastner2,3,5,6, David Goldhaber-Gordon2,3,† 1Department of Applied Physics, Stanford University, 348 Via Pueblo Mall, Stanford, CA 94305, USA. 2Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.