S. Bonetti^1,8

• ¹Department of Physics, Stockholm University, Stockholm, Sweden
• ²Physics Department, ETH Zürich, Zürich, Switzerland
• ³Institute of Applied Physics, Bern University, Bern, Switzerland
• ⁴CNR-SPIN, Fisciano (Salerno), Italy, c/o Universitá di Salerno, Fisciano (Salerno), Italy
• ⁵SLAC National Accelerator Laboratory, Menlo Park, USA
• ⁶Department of Physics, Temple University, Philadelphia, USA
• ⁷Department of Physics, University of California, Berkeley, USA
• ⁸Department of Molecular Sciences and Nanosystems, Ca’ Foscari University of Venice, Venice, Italy

• ^*These authors contributed equally to this work.
• ^†Contact author: mbasini@phys.ethz.ch