Durchstimmbarer Magnetismus in massiven Ferromagneten durch reversiblen Einbau von Ionen

• Antragsteller: Professor Dr.-Ing. Horst Hahn, seit 10/2017
• Fachliche Zuordnung: Herstellung und Eigenschaften von Funktionsmaterialien ; Experimentelle Physik der kondensierten Materie
• Förderung: Förderung von 2015 bis 2020
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 278066865

• Erstellungsjahr: 2019

Zusammenfassung der Projektergebnisse

Control of magnetism using low-voltage electric fields (magnetoelectric effect -ME), instead of dissipative flowing currents, is considered as a next generation technology to replace conventional methods of data storage, information processing, signal sensing, and actuation. In the course of the project a concept of voltage-driven, reversible electrochemistry such as ion-exchange (as known in batteries) and near-surface chemistry (as known in supercapacitors) was put to test in order to create strong ME effect. The undertaken studies covered three different classes of magnetic materials with quite different magnetic interactions - insulating super-exchange coupled ferrimagnets; strongly spin-electron correlated oxides with competing super- and double-exchange interactions; and metallic magnetic alloys with itinerant magnetism. In magnetic insulating and conducting oxides the electrochemical charging leads to the change in the valance state of the magnetic cations and to the modification of the magnetic interactions between the cations. In strongly correlated spin-electron systems, the voltage-driven magnetic switching was reached by triggering magnetic phase transitions between the competing magnetic states. Thanks to the extremely effective voltage-induced charge accumulation, which is made possible by the electrochemical methods, it is shown that: • A complete on/off voltage-driven magnetism switching can be realized for insulating and conducting, strong ferro- and ferrimagnets. • The voltage control of magnetism can be extended from the surface of the material deep to its volume. • The electrochemically-driven ME effect can be very diverse in terms of the variety of materials and material’s morphologies, and physical mechanisms identified behind the ME coupling. Being electrochemically-driven, the charging processes are generally slower than in the conventional electric field-effect devices; however, owing to the strength of the controllable magnetic response, various possibilities for novel applications involving sensing and micromagnetic actuation can be anticipated. There are opportunities, for example, in microfluidics, or in sorting/guiding of magnetic species that can either be biological substances (cells, DNAs) or Janus particles designed for drug delivery.

Projektbezogene Publikationen (Auswahl)

• Adv. Funct. Mater. 2016, 26, 7507
  S. Dasgupta, B. Das, Q. Li, D. Wang, T. T. Baby, S. Indris, M. Knapp, H. Ehrenberg, K. Fink, R. Kruk, H. Hahn
  
• J. Mater. Chem. C 2016, 4, 8889
  Reitz, C. Suchomski, D. Wang, H. Hahn, T. Brezesinski
  
• ACS Appl. Mater. Interfaces 2017, 9, 22799
  Reitz, D. Wang, D. Stoeckel, A. Beck, T. Leichtweiss, H. Hahn, T. Brezesinski
  
• Nat. Commun. 2017, 8, 15339
  Molinari, P. M. Leufke, C. Reitz, S. Dasgupta, R. Witte, R. Kruk, H. Hahn
  
• ACS Appl. Nano Mater. 2018, 1, 65
  L. A. Dubraja, C. Reitz, L. Velasco, R. Witte, R. Kruk, H. Hahn, T. Brezesinski
  
• Adv. Mater. 2018, 30, 1703908
  A. Molinari, H. Hahn, R. Kruk
  
• Adv. Mater. 2019, 31, 1806662
  A. Molinari, H. Hahn, R. Kruk
  
• J. Mater. Chem. A, 2019
  R. Singh, R. Witte, X. Mu, T. Brezesinski, H. Hahn, R. Kruk, B. Breitung