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TT: Fachverband Tiefe Temperaturen
TT 30: Complex Oxides
TT 30.5: Vortrag
Mittwoch, 29. März 2023, 10:30–10:45, HSZ 204
Directional ballistics in ultra-pure delafossite metals — •Michal Moravec1,2, Graham Baker3, Maja D. Bachmann1,2, Philippa H. McGuinness1,2, Markus König1, Seunghyun Khim1, and Andrew P. Mackenzie1,2 — 1Max Planck Institute for Chemical Physics of Solids, Dresden, Germany — 2School of Physics and Astronomy, University of St Andrews, St Andrews, United Kingdom — 3University of British Columbia, Vancouver, Canada
Studying electrical transport in extremely pure materials has led to the discovery of novel phenomena. The delafossite metals, with their two-dimensional electronic structure and mean free paths in excess of 20 µm, are a recent addition to the ultra-pure materials class. Here we study electrical transport in bars of varied width in delafossite metals PdCoO2 and PtCoO2. The bar-like structures are sculpted in two crystal orientations using the focused ion beam and sequentially narrowed across the width corresponding to the mean free path. We observe a cross-over from Ohmic to ballistic transport and gradual increase in resistivity anisotropy between the two orientations, as the channel is narrowed. This anisotropy is not allowed by the symmetry of the bulk crystal lattice; it is an example of symmetry lowering due to the imposition of shapes of finite size and the Fermi surface anisotropy [1]. We also complement our measurements with numerical solutions to the Boltzmann equation including the ARPES Fermi surface parametrisation. We obtain a good qualitative agreement with resistivity the data.
[1] M.D. Bachmann et al. Nat. Phys. 18, 819 (2022)