Regensburg 2019 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 2: Microstructure of Thin Films / Crystal Structure

KFM 2.4: Vortrag

Montag, 1. April 2019, 10:50–11:10, PHY 5.0.20

Distinctive bond breaking in crystalline phase-change materials and fingerprints for metavalent bonding — •Stefan Maier¹, Oana Cojocaru-Mirédin¹, Min Zhu¹, Antonio Mio¹, Jens Keutgen¹, Michael Küpers², Yuan Yu¹, Ju-Young Cho¹, Richard Dronskowski², and Matthias Wuttig^1,3 — ¹I. Institute of Physics (IA), RWTH Aachen University, 52074 Aachen, Germany — ²Institute of Inorganic Chemistry, RWTH Aachen University, 52056 Aachen, Germany — ³JARA-FIT Institute Green-IT, RWTH Aachen University and Forschungszentrum Jülich, 52056 Aachen, Germany

The field evaporation of a number of crystalline and amorphous phase-change materials and other intermetallic compounds was studied by laser-assisted atom probe tomography. A high probability of multiple detector events (i.e. more than one ion detected per laser pulse was found for the crystalline materials. Amorphous phase-change materials and other materials showing classical metallic or covalent bonding, exhibit low probabilities. This unusual field evaporation is unlike any other known mechanism to result in high probabilities for multiple detector events. Hence, in the presented examples, laser-assisted field evaporation reveals striking differences in bond breaking. This is indicative for pronounced differences in the bonding mechanism (which we call metavalent bonding) and it implies the presence of chemical bonds, which differ significantly from classical covalent, ionic and metallic bonds. This is supported by other fingerprints, which are sensitive towards chemical bonding such as the optical dielectric constant.