1. Adolphe Merkle Institute and Fribourg Center for Nanomaterials, University of Fribourg, 1723 Marly, Switzerland, Laboratory for Neutron Scattering, ETH Zürich & Paul Scherrer Institut, 5232 Villigen PSI, Switzerland, Institute for Geophysics, ETH Zürich, Switzerland, and Swiss Light Source, Paul Scherrer Institut, 5232 Villigen PSI, Switzerland