Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA Nanociencia), Campus Universitario de Cantoblanco, Calle Faraday 9, 28049 Madrid, Spain
Andre Schirmeisen
Institute of Applied Physics, Justus-Liebig Universität Giessen, Heinrich-Buff-Ring 16, 35392 Giessen, Germany
Carlos M. Pina
Department of Crystallography and Mineralogy, Complutense University of Madrid, 28040 Madrid, Spain
Udo Becker
Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109-1005, USA
