1. IMEC Kapeldreef 75, B-3001 Leuven, Belgium
2. Department of Electrical Engineering ESAT, KU Leuven, Kasteelpark Arenberg 10, B-3001 Leuven, Belgium
3. Department of Materials, ETH Zurich, 8093 Zürich, Switzerland
4. Univ. Grenoble Alpes, CEA, CNRS, Grenoble INP, SPINTEC, 38000 Grenoble, France