Department Colloquium: Resolving the interfacial behaviour in complex magnetic and superconducting nanostructures

  • Date: –11:15
  • Location: Ångströmlaboratoriet, Lägerhyddsvägen 1 Häggsalen
  • Lecturer: Sean Langridge, ISIS Neutron and Muon Source, Didcot, UK
  • Contact person: Björgvin Hjörvarsson
  • Seminarium

Quantifying the interfacial behaviour of nanoscale magnetic systems is key to understanding a wide range of solid state physics phenomena. Moreover, such behaviour often results in useful functionality that can be exploited in devices with applications in efficient data storage and processing. Such devices will consist of planar geometries and contain multiple active interfaces. Spin diffusion lengths in ferromagnetic metals are typically much less than 100 nm. This lengthscale gives an indication of the resolution required to spatially resolve interfacial physics such as: proximity magnetism, the spin-Seebeck effect, topological insulators and superconducting spintronics. Providing a quantitative understanding of such phenomena presents a significant experimental challenge. The interfaces of interest are often buried and not readily accessible to more conventional macroscopic techniques. Neutron techniques provide unparalleled quantitative access to such systems through the exploitation of polarized neutrons in reflection and small angle scattering geometries.

In this talk we shall introduce some of the topical systems we have recently examined. Examples will be taken from topological matter [1], materials for magnonics [2], and ferromagnetic/superconducting heterostructures [3,4].

[1] Spencer, C. S. et al. Helical magnetic structure and the anomalous and topological Hall effects in epitaxial B20 Fe1−yCoyGe films. Phys. Rev. B 97, 214406 (2018).

[2] Zhan, X. Z. et al. Probing the Transfer of the Exchange Bias Effect by Polarized Neutron Reflectometry. Sci Rep 9, 6708 (2019).

[3] Singh, S. et al. Superconductivity-driven negative interfacial magnetization in YBa2Cu3O7−δ/SrTiO3/La0.67Sr0.33MnO3 heterostructures. Appl. Phys. Lett. 116, 022406 (2020).

[4] Vaughan, M. et al. On the Origin of Superconductivity at Nickel-Bismuth Interfaces. arXiv:1911.10427 [cond-mat] (2019).